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CVE-2026-107280 — async-http-client

Fix: AsyncHttpClient/async-http-client@3302678

CVE-2026-107280 is a CWE-1275 vulnerability in org.asynchttpclient:async-http-client. A fix is available for org.asynchttpclient:async-http-client — see the affected versions and patch details below.

AsyncHttpClient: Cookie Domain attribute is not checked against the public suffix list, so a cookie can be set for co.uk

Also known asGHSA-f9m8-cv68-674w
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 22, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-107280.

EPSS Exploitation Probability

via FIRST.org ↗
0.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs17th percentile — riskier than 17% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected
☕org.asynchttpclient:async-http-client☕org.asynchttpclient:async-http-client

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

Impact

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 Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
☕Mavenorg.asynchttpclient:async-http-client≥ 3.0.0&&< 3.0.133.0.13org.asynchttpclient:async-http-client:3.0.13
☕Mavenorg.asynchttpclient:async-http-client≥ 2.0.0&&< 2.16.12.16.1org.asynchttpclient:async-http-client:2.16.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.asynchttpclient:async-http-client, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update org.asynchttpclient:async-http-client to 3.0.13 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-107280 is resolved across your whole dependency graph.

  3. Workarounds

    Put an independent control in front of the weakness: restrict the affected endpoint or interface to trusted networks, require an additional authentication factor or proxy-level check, and invalidate existing sessions and credentials in case the flaw has already been used.

Frequently Asked Questions

### Impact 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
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CVE-2026-107280: async-http-client — Fixed in 3.0.13