CVE catalog

CVE-2026-21428

cpp-httplib: CVE-2026-21428

Severity: High · CVSS 8.7CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Published: Jan 1, 2026, 5:54:43 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.40% · Oct 25, 2026

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.0, the ``write_headers`` function does not check for CR & LF characters in user supplied headers, allowing untrusted header value to escape header lines. This vulnerability allows attackers to add extra headers, modify request body unexpectedly & trigger an SSRF attack. When combined with a server that supports http1.1 pipelining (springboot, python twisted etc), this can be used for server side request forgery (SSRF). Version 0.30.0 fixes this issue.

Vulnerable and fixed packages

Distribution-reported package versions and fixes. These do not depend on matching against the OpenFactory package catalog.

Distribution	Package	Release	Version	Status
Debian	cpp-httplib	sid	`0.41.0+ds-3`	fixed
Debian	cpp-httplib	forky	`0.41.0+ds-3`	fixed
Debian	cpp-httplib	trixie	`0.18.7-1+deb13u1`	vulnerable
Debian	cpp-httplib	trixie-security	`0.18.7-1+deb13u1`	vulnerable
Debian	cpp-httplib	bookworm	`0.11.4+ds-1+deb12u1`	vulnerable
Opensuse	cpp-httplib	tumbleweed	`0.38.0-1.1`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	cpp-httplib	source	sid	`0.41.0+ds-3`	not yet assigned	Not reported	[1124586]
Debian	cpp-httplib	source	forky	`0.41.0+ds-3`	not yet assigned	Not reported	[1124586]
Debian	cpp-httplib	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1124586]
Debian	cpp-httplib	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1124586]
Opensuse	cpp-httplib	rpm	tumbleweed	`0.38.0-1.1`	Not reported	OPENSUSE-SU-2026:10435-1	Not reported

[Debian bug #1124586]

OpenFactory catalog packages

[Debian 12 (Bookworm)]

[libcpp-httplib0.11]Affected
Source package: [cpp-httplib]
Details (2)
- 0.11.4+ds-1+deb12u1 · amd64 · bookworm
  Affected
  dsa · cpp-httplib · debian · bookworm; dsa · cpp-httplib · debian · 12
- 0.11.4+ds-1+deb12u1 · arm64 · bookworm
  Affected
  dsa · cpp-httplib · debian · bookworm; dsa · cpp-httplib · debian · 12
[libcpp-httplib-dev]Affected
Source package: [cpp-httplib]
Details (2)
- 0.11.4+ds-1+deb12u1 · amd64 · bookworm
  Affected
  dsa · cpp-httplib · debian · bookworm; dsa · cpp-httplib · debian · 12
- 0.11.4+ds-1+deb12u1 · arm64 · bookworm
  Affected
  dsa · cpp-httplib · debian · bookworm; dsa · cpp-httplib · debian · 12

[Debian 13 (Trixie)]

[libcpp-httplib0.18]Affected
Source package: [cpp-httplib]
Details (4)
- 0.18.7-1+deb13u1 · amd64 · trixie
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · amd64 · trixie-security
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie-security
  Affected
  dsa · cpp-httplib · debian · 13
[libcpp-httplib0.41]Affected
Source package: [cpp-httplib]
Details (2)
- 0.41.0+ds-3~bpo13+1 · amd64 · trixie-backports
  Affected
  dsa · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · arm64 · trixie-backports
  Affected
  dsa · cpp-httplib · debian · 13
[libcpp-httplib-dev]Affected
Source package: [cpp-httplib]
Details (6)
- 0.18.7-1+deb13u1 · amd64 · trixie
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie
  Affected
  dsa · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · amd64 · trixie-backports
  Affected
  dsa · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · arm64 · trixie-backports
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · amd64 · trixie-security
  Affected
  dsa · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie-security
  Affected
  dsa · cpp-httplib · debian · 13

[openSUSE Tumbleweed]

[cpp-httplib-devel]Unknown
Source package: [cpp-httplib]
Details (1)
- 0.49.0-1.2 · x86_64 · tumbleweed
  Unknown · Fixed: 0.38.0-1.1
  Version impact unknown
  dsa · cpp-httplib · opensuse · tumbleweed
[libcpp-httplib0_49]Unknown
Source package: [cpp-httplib]
Details (1)
- 0.49.0-1.2 · x86_64 · tumbleweed
  Unknown · Fixed: 0.38.0-1.1
  Version impact unknown
  dsa · cpp-httplib · opensuse · tumbleweed

Observed: Oct 27, 2026, 10:13:49 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX]