CVE-2026-34441: yhirose cpp-httplib · HTTP Request/Response Smuggling
Affects yhirose cpp-httplibSource CVE Database V5
Not known to be exploited · CVSS 4.8 Medium : upgrade to 0.40.0 when convenient.
Data as of 30 Oct 2026, 11:52 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.40.0
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:NExploitation evidence
Disclosed: evidence found.
CVE published 31 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.
What to do
Upgrade cpp-httplib and yhirose/cpp-httplib to 0.40.0.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| yhirosecpp-httplib | Affected
| Fixed in
|
GitHubyhirose/cpp-httplibpkg:github/yhirose/cpp-httplibOther threats | Affected
| Fixed in
|
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AI-suggested
This vulnerability has been patched in cpp-httplib version 0.40.0. Users should upgrade to version 0.40.0 or later to remediate this issue. No additional mitigation steps are indicated by the vendor advisory.
Description
cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.40.0, cpp-httplib is vulnerable to HTTP Request Smuggling. The server's static file handler serves GET responses without consuming the request body. On HTTP/1.1 keep-alive connections, the unread body bytes remain on the TCP stream and are interpreted as the start of a new HTTP request. An attacker can embed an arbitrary HTTP request inside the body of a GET request, which the server processes as a separate request. This issue has been patched in version 0.40.0.