CVE-2026-29076 | cpp-httplib: Stack Overflow Denial of Service (DoS) via std::regex in multipart filename parsing

Exp

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: 2026-03-07 Last update: 2026-03-09 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-29076 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.05%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-29076

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-29076

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-13 0.04% 0.05% +0.01%
2 2026-03-08 — 0.04% —

Full EPSS history (2 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-29076

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.9 3.1 MEDIUM
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:H)
Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N)
Doesn’t really leak secrets in a meaningful way.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 2.2 3.6 [email protected]

Weakness enumeration for CVE-2026-29076

OS Trackers for CVE-2026-29076

vendor priority summary link
debian not yet assigned CVE-2026-29076 not yet assigned priority: Debian including 1 source packages (cpp-httplib), 4 status rows across 4 suites (bookworm, forky, sid, trixie): open 2, resolved 2. https://security-tracker.debian.org/tracker/CVE-2026-29076
redhat medium — https://access.redhat.com/security/cve/CVE-2026-29076
suse medium CVE-2026-29076 severity moderate: SUSE including 2 source package names (cpp-httplib-devel-0.38.0-1.1, libcpp-httplib0_38-0.38.0-1.1), 2 product×package rows across 1 product lines (openSUSE Tumbleweed): Fixed 2. https://www.suse.com/security/cve/CVE-2026-29076/
ubuntu medium CVE-2026-29076 medium priority: Ubuntu including 1 source packages (cpp-httplib), 4 status rows across 4 suites (jammy, noble, questing, upstream): needs-triage 4. https://ubuntu.com/security/CVE-2026-29076

Affected software / configurations for CVE-2026-29076

Vendor Product Version Raw CPE
yhirose cpp-httplib < 0.37.0 cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*

References for CVE-2026-29076

cvelogic Threat Intelligence