GHSA-F9M8-CV68-674W
Vulnerability from github – Published: 2026-10-08 16:30 – Updated: 2026-10-08 16:30Impact
The cookie store decides whether a Domain attribute may be accepted using only the domain-matching rule of RFC 6265 Section 5.1.3, which asks whether the request host is the domain or ends with a dot followed by it. Section 5.3 step 5, which additionally requires rejecting a Domain that is a public suffix, is not implemented anywhere in the client.
So a host under a multi-label public suffix can set a cookie for the suffix itself, and the store then hands it to every other host under that suffix:
attacker.co.uk -> Set-Cookie: SID=attacker-value; Domain=co.uk; Path=/
bank.co.uk -> Cookie: SID=attacker-value
Domain=uk works the same way. The attacker needs only a site under the same suffix as the victim, which for suffixes such as co.uk, com.au, or github.io is trivially obtainable.
Depending on what the application does with the cookie, this is session fixation, or it overwrites a session the victim site set, or it lets the attacker plant a value the victim site trusts.
Affected versions
- 3.x: up to and including 3.0.12
- 2.x: up to and including 2.16.0
Relationship to CVE-2026-55688
CVE-2026-55688 (GHSA-m452-q8c9-rg2f) covered the direct form of this, where a host sets a Domain naming an unrelated host, and that form is genuinely fixed: attacker.co.uk can no longer set Domain=bank.co.uk, and this was verified as a control. What that fix did not add is the public suffix test, so setting Domain=co.uk still reaches bank.co.uk. This advisory covers only the residual.
Patches
Fixed in 3.0.13 on the 3.x line. The ICANN section of the Mozilla public suffix list is bundled with the client and a Domain matching it is rejected, honouring the list's wildcard and exception rules. The list is data and goes stale, so a suffix added upstream after a release is not recognised until the bundled copy is refreshed. The 2.x line is not yet fixed.
Workarounds
Do not share one CookieStore across origins that are not mutually trusted. Supplying a CookieStore implementation that rejects Domain values which are public suffixes also avoids it.
Details
ThreadSafeCookieStore.domainsMatch is requestDomain.equals(cookieDomain) || requestDomain.endsWith('.' + cookieDomain). It is used both to accept a Domain on storage and to select cookies for a request, and neither call site consults a public suffix list. A search of the client for any public suffix or effective TLD handling returns nothing.
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.0.12"
},
"package": {
"ecosystem": "Maven",
"name": "org.asynchttpclient:async-http-client"
},
"ranges": [
{
"events": [
{
"introduced": "3.0.0"
},
{
"fixed": "3.0.13"
}
],
"type": "ECOSYSTEM"
}
]
},
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 2.16.0"
},
"package": {
"ecosystem": "Maven",
"name": "org.asynchttpclient:async-http-client"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.16.1"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-107280"
],
"database_specific": {
"cwe_ids": [
"CWE-1275"
],
"github_reviewed": true,
"github_reviewed_at": "2026-10-08T16:30:53Z",
"nvd_published_at": "2026-10-07T22:17:03Z",
"severity": "MODERATE"
},
"details": "### Impact\nThe cookie store decides whether a `Domain` attribute may be accepted using only the domain-matching rule of RFC 6265 Section 5.1.3, which asks whether the request host is the domain or ends with a dot followed by it. Section 5.3 step 5, which additionally requires rejecting a `Domain` that is a public suffix, is not implemented anywhere in the client.\n\nSo a host under a multi-label public suffix can set a cookie for the suffix itself, and the store then hands it to every other host under that suffix:\n\n```\nattacker.co.uk -\u003e Set-Cookie: SID=attacker-value; Domain=co.uk; Path=/\nbank.co.uk -\u003e Cookie: SID=attacker-value\n```\n\n`Domain=uk` works the same way. The attacker needs only a site under the same suffix as the victim, which for suffixes such as `co.uk`, `com.au`, or `github.io` is trivially obtainable.\n\nDepending on what the application does with the cookie, this is session fixation, or it overwrites a session the victim site set, or it lets the attacker plant a value the victim site trusts.\n\n### Affected versions\n* 3.x: up to and including 3.0.12\n* 2.x: up to and including 2.16.0\n\n### Relationship to CVE-2026-55688\nCVE-2026-55688 (GHSA-m452-q8c9-rg2f) covered the direct form of this, where a host sets a `Domain` naming an unrelated host, and that form is genuinely fixed: `attacker.co.uk` can no longer set `Domain=bank.co.uk`, and this was verified as a control. What that fix did not add is the public suffix test, so setting `Domain=co.uk` still reaches `bank.co.uk`. This advisory covers only the residual.\n\n### Patches\nFixed in 3.0.13 on the 3.x line. The ICANN section of the Mozilla public suffix list is bundled with the client and a `Domain` matching it is rejected, honouring the list\u0027s wildcard and exception rules. The list is data and goes stale, so a suffix added upstream after a release is not recognised until the bundled copy is refreshed. The 2.x line is not yet fixed.\n\n### Workarounds\nDo not share one `CookieStore` across origins that are not mutually trusted. Supplying a `CookieStore` implementation that rejects `Domain` values which are public suffixes also avoids it.\n\n### Details\n`ThreadSafeCookieStore.domainsMatch` is `requestDomain.equals(cookieDomain) || requestDomain.endsWith(\u0027.\u0027 + cookieDomain)`. It is used both to accept a `Domain` on storage and to select cookies for a request, and neither call site consults a public suffix list. A search of the client for any public suffix or effective TLD handling returns nothing.",
"id": "GHSA-f9m8-cv68-674w",
"modified": "2026-10-08T16:30:53Z",
"published": "2026-10-08T16:30:53Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/AsyncHttpClient/async-http-client/security/advisories/GHSA-f9m8-cv68-674w"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-107280"
},
{
"type": "WEB",
"url": "https://github.com/AsyncHttpClient/async-http-client/commit/330267895fe0bdb41bbd027ea6b151d38ee7c23d"
},
{
"type": "WEB",
"url": "https://github.com/AsyncHttpClient/async-http-client/commit/d1f0ccec417092098d40242fee7dfac84bb3c21f"
},
{
"type": "PACKAGE",
"url": "https://github.com/AsyncHttpClient/async-http-client"
},
{
"type": "WEB",
"url": "https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-2.16.1"
},
{
"type": "WEB",
"url": "https://github.com/AsyncHttpClient/async-http-client/releases/tag/async-http-client-project-3.0.13"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:N",
"type": "CVSS_V4"
}
],
"summary": "AsyncHttpClient: Cookie Domain attribute is not checked against the public suffix list, so a cookie can be set for co.uk"
}
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.
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.
Browse all ATT&CK techniques and the vulnerabilities related to each.
Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.