Vulnerability in Yhirose Cpp-Httplib
CVE-2026-29076
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H.
EPSS exploit prediction
EPSS: 0.006 (48.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 48th percentile — 48.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: +0.000
Affected products
- Yhirose Cpp-Httplib — versions < 0.37.0
Weakness classification (CWE)
References
- github.com/yhirose/cpp-httplib/security/advisories/GHSA-qq6v-r583-3h69 (Exploit, Vendor Advisory)
- github.com/yhirose/cpp-httplib/commit/de296af3eb5b0d5c116470e033db900e4812c5e6 (Patch)
- github.com/yhirose/cpp-httplib/releases/tag/v0.37.0 (Product, Release Notes)
Frequently asked questions
- What is CVE-2026-29076?
- CVE-2026-29076 is a medium-severity vulnerability in Yhirose Cpp-Httplib, classified under Uncontrolled Recursion. CVSS score: 5.9/10. Published 2026-03-07.
- How severe is CVE-2026-29076?
- Medium severity. CVSS v3 base score is 5.9 out of 10.