CVE-2026-43972Network attack vector

Cross-origin cookie injection via unvalidated push authority

Published Jun 8, 2026 · Updated Jun 8, 2026

Origin validation error in Nine Nines Gun before 2.4.0 allows remote attackers to inject cross-origin cookies through HTTP/2 server push. The gun_http2:push_promise_frame/7 routine stores the server-supplied :authority without matching it to the connection origin, and headers_frame/9 passes that value to the shared cookie store. A configured cookie_store, HTTP/2 server push, and a malicious or compromised server are required; planted cookies enable session fixation and account takeover when they replace a legitimate session token.

CVSS severity6.3
Medium
EPSS probability0.17%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Origin validation error in Nine Nines Gun before 2.4.0 allows remote attackers to inject cross-origin cookies through HTTP/2 server push. The gun_http2:push_promise_frame/7 routine stores the server-supplied :authority without matching it to the connection origin, and headers_frame/9 passes that value to the shared cookie store. A configured cookie_store, HTTP/2 server push, and a malicious or compromised server are required; planted cookies enable session fixation and account takeover when they replace a legitimate session token.

The record

CVE
CVE-2026-43972
Published
Jun 8, 2026
Updated
Jun 8, 2026
Vendor
Nine Nines
Product
Gun
Classifications
CWE-346, CAPEC-61
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 8, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 8, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.0.0 <2.4.0
  2. Affected versionversion=871989eef53663285c165fdfb83a5918ebe00d41 <567863ff53802fed21c3b3f25812db7f7ae29676

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Nine Nines · Gunversion=2.0.0 <2.4.0; version=871989eef53663285c165fdfb83a5918ebe00d41 <567863ff53802fed21c3b3f25812db7f7ae29676

Published CVSS scores

7.2NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N
6.3EEFCVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-346Origin Validation Error
CAPEC-61Session Fixation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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