VulnerabilityAnalyzed

CVE-2026-29076

An attacker can send a single HTTP POST request with a crafted filename* parameter that causes uncontrolled stack growth, resulting in a stack overflow (SIGSEGV) that crashes the server process.

MEDIUM 5.9EPSS 0.60%

Does this matter?

Lower severity and a low EPSS score (0.60%). Track it; it rarely justifies an emergency change on its own.

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.37.0, cpp-httplib uses std::regex (libstdc++) to parse RFC 5987 encoded filename* values in multipart Content-Disposition headers. The regex engine in libstdc++ implements backtracking via deep recursion, consuming one stack frame per input character. An attacker can send a single HTTP POST request with a crafted filename* parameter that causes uncontrolled stack growth, resulting in a stack overflow (SIGSEGV) that crashes the server process. This issue has been patched in version 0.37.0.

CVSS 3.1: 5.9 MEDIUMCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS: 0.60% probability · 47th percentile
CISA KEV: Not listed
Weakness: CWE-674, CWE-1333
Affected: yhirose/cpp-httplib
Source: security-advisories@github.com

References

https://github.com/yhirose/cpp-httplib/commit/de296af3eb5b0d5c116470e033db900e4812c5e6Patch
https://github.com/yhirose/cpp-httplib/releases/tag/v0.37.0Product, Release Notes
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-qq6v-r583-3h69Exploit, Vendor Advisory

Source: NVD record, EPSS from FIRST.org, KEV from CISA. Refreshed daily.