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VulnerabilityPublished

CVE-2026-43972: ninenines gun · Origin Validation Error

Affects ninenines gunSource CVE Database V5

0

Not known to be exploited · CVSS 6.3 Medium : upgrade to 2.4.0 when convenient.

Data as of 28 Oct 2026, 05:11 UTC

CVSS 4.0 base score
6.3Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2.4.0, 567863ff53802fed21c3b3f25812db7f7ae29676
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 8 Jun 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade gun to 2.4.0; gun to 567863ff53802fed21c3b3f25812db7f7ae29676.

Affected software

ProductAffectedFixed in
nineninesgunAffected
  • >=2.0.0 <2.4.0
Fixed in
  • 2.4.0
nineninesgunAffected
  • ≥ 871989eef53663285c165fdfb83a5918ebe00d41, < 567863ff53802fed21c3b3f25812db7f7ae29676
Fixed in
  • 567863ff53802fed21c3b3f25812db7f7ae29676
Hexgunpkg:hex/gunOther threatsAffected
  • >=2.0.0 <2.4.0
  • =2.0.0
Fixed in
  • 2.4.0
GitHubgunpkg:github/gunOther threatsAffected
  • >=2.0.0 <2.4.0
Fixed in
  • 2.4.0

CPE configurations (1)

  • cpe:2.3:a:ninenines:gun:*:*:*:*:*:*:*:*

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

If you cannot patch yet, avoid using vulnerable versions of gun with untrusted HTTP/2 servers or disable HTTP/2 PUSH_PROMISE handling if possible.

Description

CVE-2026-43972 is an origin validation error vulnerability in the ninenines gun HTTP/2 module (gun_http2). It allows a malicious or compromised HTTP/2 server to inject cookies scoped to arbitrary third-party domains into the client's cookie store via unvalidated PUSH_PROMISE authority headers. This violates HTTP/2 protocol requirements and can enable session fixation and potential account takeover without user interaction. The issue affects gun versions from 2.0.0 up to but not including 2.4.0.

References

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