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No exploitation reported

CVE-2026-124040

CivetWeb through 1.16 HTTP/2 Use-After-Free via Stale Pseudo-Header State

No exploitation reported by the sources we read.

  • Published2026-11-06
  • WeaknessCWE-416

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

CivetWeb through 1.16, when built with USE_HTTP2 and enable_http2 on, contains a use-after-free vulnerability in handle_http2() that retains freed :method and :path pointers. Unauthenticated remote attackers can send a later HEADERS frame omitting these pseudo-headers to influence request method or path seen by access rules, or crash the server.

Timeline

dates in UTC
  1. 2026-11-0619:14CVE publishedCNA

Versions per branch

Products declared by the CNA

As VulnCheck, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • civetwebother versions: not affected
    Affected
    • ≤ 1.16no fix statedcustom

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-11-06

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-124040 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Metasploit modules
none listed
Metasploit Framework

Sources

  • CNACVSS 4.09.22026-11-06
  • CNACVSS 3.18.12026-11-06
  • NVDCVSS 3.18.1read 2026-11-06
  • CNAweakness (CWE)CWE-4162026-11-06
  • NVDweakness (CWE)CWE-416read 2026-11-06

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
CVSS 4.0 vector
CVSS:4.0/AV:N/AC:H/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Published
2026-11-06
Last Modified
2026-11-06
NVD status
Deferred

Frequently asked questions

What is CVE-2026-124040?

CivetWeb through 1.16, when built with USE_HTTP2 and enable_http2 on, contains a use-after-free vulnerability in handle_http2() that retains freed :method and :path pointers. Unauthenticated remote attackers can send a later HEADERS frame omitting these pseudo-headers to influence request method or path seen by access rules, or crash the server.

Is CVE-2026-124040 actively exploited?

Active exploitation of CVE-2026-124040 has not been confirmed.

What is the CVSS score for CVE-2026-124040?

CVE-2026-124040 has a CVSS v3 base score of 8.1 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H.

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