Vulnerability-Lookup

CVE-2026-87996 (GCVE-0-2026-87996)

Vulnerability from cvelistv5 – Published: 2026-09-09 21:28 – Updated: 2026-09-10 13:48

Title

Open WebUI: SSRF into internal services via DNS rebinding in the Playwright web loader

Summary

Open WebUI is an extensible, feature-rich, and user-friendly self-hosted AI platform. From 0.9.6 until 0.11.1, SafePlaywrightURLLoader in backend/open_webui/retrieval/web/utils.py validated a user-controlled hostname in Python and then let the Playwright browser resolve it again in the sync and async request interceptors. An authenticated user controlling authoritative DNS could return a public address to validation and an internal address to the browser, exposing responses from internal services or cloud metadata through web search or URL ingestion. This issue is fixed in version 0.11.1.

Severity

7.7 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-10 13:48 UTC

CWE

CWE-367 - Time-of-check Time-of-use (TOCTOU) Race Condition
CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M mitre root

References

4 references

URL	Tags
https://github.com/open-webui/open-webui/security…	x_refsource_CONFIRM
https://github.com/open-webui/open-webui/pull/28634	x_refsource_MISC
https://github.com/open-webui/open-webui/commit/2…	x_refsource_MISC
https://github.com/open-webui/open-webui/releases…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version	CPE status
open-webui	open-webui	Affected: >= 0.9.6, < 0.11.1	guessed

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-87996

Vulnerability from fkie_nvd - Published: 2026-09-09 22:18 - Updated: 2026-09-10 14:50

Severity

7.7 (High) - CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N

Summary

References

	URL	Tags
	security-advisories@github.com	https://github.com/open-webui/open-webui/commit/27402ff210bfa253445720920dfb86b15a00327b
	security-advisories@github.com	https://github.com/open-webui/open-webui/pull/28634
	security-advisories@github.com	https://github.com/open-webui/open-webui/releases/tag/v0.11.1
	security-advisories@github.com	https://github.com/open-webui/open-webui/security/advisories/GHSA-4v28-j6q3-5m4r
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/open-webui/open-webui/security/advisories/GHSA-4v28-j6q3-5m4r

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "product": "open-webui",
          "vendor": "open-webui",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 0.9.6, \u003c 0.11.1"
            }
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    }
  ],
  "id": "CVE-2026-87996",
  "lastModified": "2026-09-10T14:50:07.813",
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GHSA-4V28-J6Q3-5M4R

Vulnerability from github – Published: 2026-09-10 15:10 – Updated: 2026-09-10 15:10

Summary

Open WebUI: SSRF into internal services via DNS rebinding in the Playwright web loader

Details

Summary

With the Playwright web loader enabled, Open WebUI checks the address behind a user-submitted URL before allowing the request, then handed the request to the browser to perform. The browser resolved the hostname a second time, on its own, and that answer was never checked. An attacker who controls the authoritative DNS for a hostname they submit can answer the first lookup with a public address and the second with an internal one, so the browser connects to an address the check exists to block. The connection-layer pinning that protects the other fetch paths could not apply here, because the request ran inside the browser rather than through our own HTTP clients.

Preconditions

WEB_LOADER_ENGINE=playwright. This is not the default, and deployments on the default web loader are unaffected.
A reachable Playwright browser, either local or via PLAYWRIGHT_WS_URL.
Any authenticated user who can submit a URL for ingestion or trigger a web search. No administrator role is required.
Control of the authoritative DNS for a hostname the attacker submits, serving a short TTL and alternating answers. No timing race is needed, because the two lookups are separate queries the attacker answers differently.
Internal services the browser process can actually reach. A deployment whose browser has no route to internal addresses loses nothing here.

Impact

An authenticated user can make the server read HTTP responses from addresses only it can reach: cloud instance metadata, loopback-bound admin APIs, and internal services on the same network. The response body is fulfilled back into the page, and the loader returns that page as the document, so the content lands in the web-search or ingestion result the user receives. On a cloud host with IMDSv1 reachable, that is enough to take instance IAM credentials.

Because the intercepted request forwards the original method and headers, a page the attacker controls can also drive requests that need a header or a non-GET method, which covers the header-gated metadata endpoints. This is a read primitive; no modification of Open WebUI data and no availability impact was demonstrated. Deployments on the default web loader are not affected at all.

Fix

Fixed in 0.11.1 by commit 27402ff21 (#28634). The interceptor no longer asks the browser to perform the request. It issues the request from the SSRF-safe HTTP client instead, which resolves the hostname once and connects to that same validated address, re-validates every redirect hop, and then fulfils the browser with the response it received. Upgrading to 0.11.1 fully resolves this, and no configuration change is required.

Root cause

Affected component: SafePlaywrightURLLoader in backend/open_webui/retrieval/web/utils.py, in both the sync and async request interceptors. Affected setup: only builds running the Playwright loader engine.

The address check and the connection were performed by two different resolvers in two different processes. Validation resolved the hostname in Python and inspected the result, then the request was handed to the browser, which resolved the name again and connected to whatever it got. Playwright's request-fetch API offers no way to pin a connection to an already-validated address, so the fix that had been applied to the other fetch paths, resolving once and connecting to that same address, could not reach this one. The check was therefore an opinion about an earlier lookup rather than a constraint on the connection that followed.

Proof of concept

Reproduced against the real implementation: the validation and interception code was taken unmodified, with only the module-level configuration constants stubbed at their documented defaults, and driven against a real Chromium instance inside an unprivileged network namespace with an authoritative DNS server answering the first lookup public and the second internal. Instance metadata and a loopback service were both reached, with the response body returned through the page. A second run showed an attacker-controlled page driving the header-gated metadata sequence to completion. The path from the HTTP endpoint to the loader was traced in source rather than driven end to end.

Credits

@baeseungwon1010 — identified that the address check and the browser's own resolution are two separate lookups, so the check cannot constrain where the browser connects.

Severity

7.7 (High)


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

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "open-webui"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0.9.6"
            },
            {
              "fixed": "0.11.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-87996"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-367",
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-10T15:10:12Z",
    "nvd_published_at": "2026-09-09T22:18:47Z",
    "severity": "HIGH"
  },
  "details": "## Summary\nWith the Playwright web loader enabled, Open WebUI checks the address behind a user-submitted URL before allowing the request, then handed the request to the browser to perform. The browser resolved the hostname a second time, on its own, and that answer was never checked. An attacker who controls the authoritative DNS for a hostname they submit can answer the first lookup with a public address and the second with an internal one, so the browser connects to an address the check exists to block. The connection-layer pinning that protects the other fetch paths could not apply here, because the request ran inside the browser rather than through our own HTTP clients.\n\n## Preconditions\n- `WEB_LOADER_ENGINE=playwright`. This is not the default, and deployments on the default web loader are unaffected.\n- A reachable Playwright browser, either local or via `PLAYWRIGHT_WS_URL`.\n- Any authenticated user who can submit a URL for ingestion or trigger a web search. No administrator role is required.\n- Control of the authoritative DNS for a hostname the attacker submits, serving a short TTL and alternating answers. No timing race is needed, because the two lookups are separate queries the attacker answers differently.\n- Internal services the browser process can actually reach. A deployment whose browser has no route to internal addresses loses nothing here.\n\n## Impact\nAn authenticated user can make the server read HTTP responses from addresses only it can reach: cloud instance metadata, loopback-bound admin APIs, and internal services on the same network. The response body is fulfilled back into the page, and the loader returns that page as the document, so the content lands in the web-search or ingestion result the user receives. On a cloud host with IMDSv1 reachable, that is enough to take instance IAM credentials.\n\nBecause the intercepted request forwards the original method and headers, a page the attacker controls can also drive requests that need a header or a non-GET method, which covers the header-gated metadata endpoints. This is a read primitive; no modification of Open WebUI data and no availability impact was demonstrated. Deployments on the default web loader are not affected at all.\n\n## Fix\nFixed in 0.11.1 by commit `27402ff21` (#28634). The interceptor no longer asks the browser to perform the request. It issues the request from the SSRF-safe HTTP client instead, which resolves the hostname once and connects to that same validated address, re-validates every redirect hop, and then fulfils the browser with the response it received. Upgrading to 0.11.1 fully resolves this, and no configuration change is required.\n\n## Root cause\nAffected component: `SafePlaywrightURLLoader` in `backend/open_webui/retrieval/web/utils.py`, in both the sync and async request interceptors. Affected setup: only builds running the Playwright loader engine.\n\nThe address check and the connection were performed by two different resolvers in two different processes. Validation resolved the hostname in Python and inspected the result, then the request was handed to the browser, which resolved the name again and connected to whatever it got. Playwright\u0027s request-fetch API offers no way to pin a connection to an already-validated address, so the fix that had been applied to the other fetch paths, resolving once and connecting to that same address, could not reach this one. The check was therefore an opinion about an earlier lookup rather than a constraint on the connection that followed.\n\n## Proof of concept\nReproduced against the real implementation: the validation and interception code was taken unmodified, with only the module-level configuration constants stubbed at their documented defaults, and driven against a real Chromium instance inside an unprivileged network namespace with an authoritative DNS server answering the first lookup public and the second internal. Instance metadata and a loopback service were both reached, with the response body returned through the page. A second run showed an attacker-controlled page driving the header-gated metadata sequence to completion. The path from the HTTP endpoint to the loader was traced in source rather than driven end to end.\n\n## Credits\n- **@baeseungwon1010** \u2014 identified that the address check and the browser\u0027s own resolution are two separate lookups, so the check cannot constrain where the browser connects.",
  "id": "GHSA-4v28-j6q3-5m4r",
  "modified": "2026-09-10T15:10:12Z",
  "published": "2026-09-10T15:10:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/security/advisories/GHSA-4v28-j6q3-5m4r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-87996"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/pull/28634"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/commit/27402ff210bfa253445720920dfb86b15a00327b"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/open-webui/open-webui"
    },
    {
      "type": "WEB",
      "url": "https://github.com/open-webui/open-webui/releases/tag/v0.11.1"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Open WebUI: SSRF into internal services via DNS rebinding in the Playwright web loader"
}

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.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.

Action not permitted

CVE-2026-87996 (GCVE-0-2026-87996)

FKIE_CVE-2026-87996

GHSA-4V28-J6Q3-5M4R

Summary

Preconditions

Impact

Fix

Root cause

Proof of concept

Credits

Tags

Sightings

Nomenclature