CVE-2026-43972

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 §10.6 / RFC 9113 §8.4, 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.

Overview

State

—

Assigner (CNA)

—

CVSS severity

high

CVSS score

8.8 / 10

CVSS vector

AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

Effective score

8.8 / 10 HIGH source: CNA overview

CWE(s)

—

Reserved

—

Published

—

Last updated

—

Source

https://www.tenable.com/cve/CVE-2026-43972

Linked Threat

CVE-2026-43972 — CVE-2026-43972

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published

2026-06-08 15:16:46 UTC

NVD last modified

2026-07-23 07:10:00 UTC

EPSS score

0.0022 (probability of exploitation in next 30 days)

EPSS percentile

12.02% vs all CVEs — higher = more likely to be exploited, as of 2026-08-01

NVD-assigned CWE(s): CWE-346 (differs from the CNA list above)

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID

EUVD-2026-35073

Assigner

EEF

Published

Jun 8, 2026, 2:12:38 PM

Updated

Jun 8, 2026, 4:34:45 PM

EUVD base score (CVSS 4.0)

6.3 / 10
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

EUVD-reported EPSS

0.2200

Vendors

ninenines

Products

gun (2.0.0 <2.4.0)

gun (871989eef53663285c165fdfb83a5918ebe00d41 <567863ff53802fed21c3b3f25812db7f7ae29676)

Aliases

GHSA-36w4-95hv-5vwg

ENISA 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 §10.6 / RFC 9113 §8.4, 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.

Vendor references (0)

References embedded in the original CVE record by the assigning CNA.

None in the CVE record.

Web references (5)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

• https://cna.erlef.org/cves/CVE-2026-43972.html tenable:cna.erlef.org
• https://github.com/ninenines/gun/commit/567863ff53802fed21c3b3f25812db7f7ae29676 tenable:github.com
• https://nvd.nist.gov/vuln/detail/CVE-2026-43972 tenable:nvd.nist.gov
• https://osv.dev/vulnerability/EEF-CVE-2026-43972 tenable:osv.dev
• https://www.cve.org/CVERecord?id=CVE-2026-43972 tenable:www.cve.org

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

• Nvd - Cve-2026-8972
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  2026-06-19 02:38 UTC
• Security Update Guide - Loading - Microsoft
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• March 13, 2026—Hotpatch KB5084597 (OS Builds 26200.7982 and 26100.7982 ...
  web:support.microsoft.com

  The following summary outlines key issues addressed by this update. The bold text within the brackets indicates the item or area of the change. [Networking] Fixed: This update addresses a security issue in the Windows Routing and Remote Access Service (RRAS) management tool. If you connect to a malicious remote server, an attacker could disrupt the tool or run code on your device. For more ...

  2026-06-19 02:38 UTC
• SAP Security Patch Day - February 2026
  web:support.sap.com

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  2026-06-19 02:38 UTC
• February's Patch Tuesday release fixes 59 flaws ... - Computerworld
  web:www.computerworld.com

  Each month, the team at Readiness analyzes the latest Patch Tuesday updates from Microsoft and provides detailed, actionable testing guidance. The company's Patch Tuesday release for February ...

  2026-06-19 02:38 UTC
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  web:www.computerworld.com

  Microsoft says it is considering a patch for a zero-day vulnerability, dubbed YellowKey, that allows attackers with access to a Windows device to bypass Bitlocker encryption protection and read ...

  2026-06-19 02:38 UTC
• Patch Tuesday: May 2026 Latest Patch Updates & Breakdown
  web:www.manageengine.com

  Unfold what this Patch Tuesday has in store for you Patch Tuesday, the unofficial term for Microsoft's scheduled security fix release on every second Tuesday of a month, has been a constant topic of discussion ever since its inception. Upcoming Webinar June 11,2026 11:30 EDT & 6:30 a.m. GMT Agenda of the Free Patch Tuesday webinar A complete breakdown of all the latest Patch Tuesday updates ...

  2026-06-19 02:38 UTC
• Oracle Critical Security Patch Update Advisory - May 2026
  web:www.oracle.com

  This Critical Security Patch Update contains 35 new security patches across the product families listed below. Please note that an MOS note summarizing the content of this Critical Security Patch Update and other Oracle Software Security Assurance activities is located at May 2026 Critical Security Patch Update: Executive Summary and Analysis.

  2026-06-19 02:38 UTC
• Patch Tuesday - June 2026 - Rapid7
  web:www.rapid7.com

  Microsoft is publishing 200 vulnerabilities on June 2026 Patch Tuesday, including an HTTP/2 denial of service vulnerability and an elevation of privilege vulnerability in PowerToys.

  2026-06-19 02:38 UTC
• Patch Tuesday June 2026: Security Updates & CVE Analysis
  web:zecurit.com

  Get the complete breakdown of Microsoft's June 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

  2026-06-19 02:38 UTC

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