CivetWeb: memory corruption

CivetWeb

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.

Do this now

Check the CivetWeb advisory for a fixed release and restrict access to affected HTTP/2 servers until one is applied.

Who should check: teams running Linux server software

Still cooking for CivetWeb.

First seen: 8 Nov 2026
Last update: 8 Nov 2026, 11:18 UTC
Identifiers: CVE-2026-124040
CVSS: 8.1
Source: news
On the menu as: Linux server software

Check this repository for exposure to one security incident from pwned.coffee. Report first, change nothing until I say so.

## CivetWeb: memory corruption
Severity: high. Patch status: fix status unknown.
Affected: CivetWeb
Ids: 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.

## Steps
1. Search the repo, its CI and infra config for CivetWeb. If present, report the version in use and whether it's affected.
2. CivetWeb <= 1.16: the CVE record names no fix; check the vendor advisory before assuming there is none. Until one ships: restrict network access to it.

## Fix by release line
| Line | State | Fix | Until then |
|---|---|---|---|
| CivetWeb <= 1.16 | not named in the CVE record | check the vendor advisory | restrict network access to it |

## Report
A table: file, product or package, version in use, affected yes/no, exact fix. Then anything a human has to check outside the repo.

If you have the pwned.coffee MCP server (https://pwned.coffee/mcp), call lookup_cve("CVE-2026-124040") for the latest, and check_repo with this repo's lockfiles, Dockerfiles and workflows for a full receipt.
Sources: https://github.com/civetweb/civetweb https://nvd.nist.gov/vuln/detail/CVE-2026-124040
https://pwned.coffee/i/handle-http2-memory-corruption-cve-2026-124040

Receipt

Exploitation: No known exploitation
Checked by hand “The CVE record names the product CivetWeb (through 1.16) and a use-after-free in its handle_http2() function; the stored title "Handle_http2: memory corruption" took the function for the product.” source
Fix by release line: Product Affected Fixed in Source
CivetWeb <= 1.16 fix not named in the CVE record: see vendor advisory CVE record (CNA) checked 13 Nov
Score: CVSS 8.1 (high). CVSS 3.1 8.1 (CNA VulnCheck) for CVE-2026-124040
Last checked: 13 Nov 2026, 16:26 UTC

Product	Affected	Fixed in	Source
CivetWeb	<= 1.16	fix not named in the CVE record: see vendor advisory	CVE record (CNA) checked 13 Nov

Sources: KEV – CVE record ✓ Vendor ✓

Sources

Follow on X

Totalone hot coffee