CVE catalog

CVE-2026-45352

Severity: Medium · CVSS 5.3CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
Published: May 29, 2026, 7:14:08 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.33% · Oct 25, 2026

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.43.4, negative chunk-size in chunked Transfer-Encoding causes unbounded memory allocation and process crash. The ChunkedDecoder::read_payload function in cpp-httplib (httplib.h) parses the chunk-size field of HTTP chunked transfer encoding using std::strtoul(). Per the C standard (§7.22.1.4), strtoul silently accepts a leading minus sign, performing unsigned wrap-around: strtoul("-2", …, 16) returns ULONG_MAX − 1 (0xFFFFFFFFFFFFFFFE). The library's only guard (line 12833) rejects ULONG_MAX (the result of "-1"), but any other negative value such as "-2" passes validation. The resulting near-maximum value is stored in chunk_remaining and controls how many bytes the server's read loop consumes from the network. This vulnerability is fixed in 0.43.4.

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`	vulnerable
Debian	cpp-httplib	forky	`0.41.0+ds-3`	vulnerable
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
Cpe	cpp-httplib	Not reported	Not reported	vulnerable
Cpe	cpp-httplib	Not reported	`0.43.4`	fixed

Fixed-version evidence

Distribution	Package	Type	Release	Fixed version	Urgency	Origin	Bugs
Debian	cpp-httplib	source	sid	`(unfixed)`	not yet assigned	Not reported	[1138578]
Debian	cpp-httplib	source	forky	`(unfixed)`	not yet assigned	Not reported	[1138578]
Debian	cpp-httplib	source	trixie	`(unfixed)`	not yet assigned	Not reported	[1138578]
Debian	cpp-httplib	source	bookworm	`(unfixed)`	not yet assigned	Not reported	[1138578]
Cpe	cpp-httplib	cpe	Not reported	`0.43.4`	Not reported	Not reported	Not reported

[Debian bug #1138578]

Notes

[trixie] cpp-httplib: Minor issue [bookworm] cpp-httplib: Minor issue

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
  nvd · cpp-httplib · debian · bookworm; nvd · cpp-httplib · debian · 12
- 0.11.4+ds-1+deb12u1 · arm64 · bookworm
  Affected
  nvd · cpp-httplib · debian · bookworm; nvd · cpp-httplib · debian · 12
[libcpp-httplib-dev]Affected
Source package: [cpp-httplib]
Details (2)
- 0.11.4+ds-1+deb12u1 · amd64 · bookworm
  Affected
  nvd · cpp-httplib · debian · bookworm; nvd · cpp-httplib · debian · 12
- 0.11.4+ds-1+deb12u1 · arm64 · bookworm
  Affected
  nvd · cpp-httplib · debian · bookworm; nvd · 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
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie
  Affected
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · 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
  nvd · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · arm64 · trixie-backports
  Affected
  nvd · cpp-httplib · debian · 13
[libcpp-httplib-dev]Affected
Source package: [cpp-httplib]
Details (6)
- 0.18.7-1+deb13u1 · amd64 · trixie
  Affected
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie
  Affected
  nvd · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · amd64 · trixie-backports
  Affected
  nvd · cpp-httplib · debian · 13
- 0.41.0+ds-3~bpo13+1 · arm64 · trixie-backports
  Affected
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · amd64 · trixie-security
  Affected
  nvd · cpp-httplib · debian · 13
- 0.18.7-1+deb13u1 · arm64 · trixie-security
  Affected
  nvd · cpp-httplib · debian · 13

Observed: Oct 27, 2026, 7:18:57 AM UTC

References

[Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX]