Vulnerability · Published Mar 7, 2026 · Assigned by GitHub_M
CVE-2026-29076cpp-httplib: Stack Overflow Denial of Service (DoS) via std::regex in multipart filename parsing
Medium 5.9
In plain English
A medium-severity regular-expression denial of service in cpp-httplib from yhirose. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official 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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | cpp-httplib | no fix listed | DEBIAN-CVE-2026-29076 |
| Debian:13 | cpp-httplib | no fix listed | DEBIAN-CVE-2026-29076 |
| Debian:14 | cpp-httplib | 0.41.0+ds-3 | DEBIAN-CVE-2026-29076 |
| Ubuntu:25.10 | cpp-httplib | no fix listed | UBUNTU-CVE-2026-29076 |
| Ubuntu:26.10 | cpp-httplib | no fix listed | UBUNTU-CVE-2026-29076 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| yhirose | cpp-httplib | < 0.37.0 |
Weakness: CWE-674, CWE-1333 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H