CVE-2026-43972

N/A Unknown
Published: June 08, 2026 Modified: June 09, 2026
View on NVD

Description

Origin Validation Error vulnerability in ninenines gun (gun_http2 module) allows cross-origin cookie injection via unvalidated HTTP/2 PUSH_PROMISE authority. In gun_http2:push_promise_frame/7, the :authority pseudo-header from an incoming PUSH_PROMISE frame is stored verbatim into the promised stream record without checking that it matches the connection's origin. When gun_http2:headers_frame/9 later processes the response headers for the promised stream, it calls gun_cookies:set_cookie_header/7 with the unvalidated server-supplied authority before any status branching and before user code can act. This violates RFC 7540 ยง10.6 / RFC 9113 ยง8.4, which require receivers to treat as a protocol error any push for a resource the server is not authoritative for. A malicious or compromised HTTP/2 server can plant cookies scoped to arbitrary third-party domains into the client's shared cookie store. This enables session fixation attacks against those domains and, if the planted cookie overrides a legitimate session token, may result in account takeover. No user interaction beyond making a normal HTTP/2 request to the attacker-controlled server is required. This issue affects gun: from 2.0.0 before 2.4.0.

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References to Advisories, Solutions, and Tools

Patch Vendor Advisory Exploit Third Party Advisory
https://cna.erlef.org/cves/CVE-2026-43972.html
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
https://osv.dev/vulnerability/EEF-CVE-2026-43972
Source: 6b3ad84c-e1a6-4bf7-a703-f496b71e49db

3 reference(s) from NVD

Quick Stats

CVSS v3 Score
N/A / 10.0
EPSS (Exploit Probability)
0.2%
12th percentile
Exploitation Status
Not in CISA KEV

Weaknesses (CWE)