Medium severity · published Mar 7, 2026
CVE-2026-29076
cpp-httplib: Stack Overflow Denial of Service (DoS) via std::regex in multipart filename parsing
5.9
CVSS
0.6%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Attack vector
Network
Complexity
High
Privileges
None
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.6% · higher than 51% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CP
cpp-httplib · yhirose
< 0.37.0 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-29076
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-29076
Patch
https://github.com/yhirose/cpp-httplib/commit/de296af3eb5b0d5c116470e033db900e4812c5e6
Product
https://github.com/yhirose/cpp-httplib/releases/tag/v0.37.0
Exploit
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-qq6v-r583-3h69
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