Improper Input Validation Affecting cpp-httplib package, versions *


Severity

Recommended
0.0
high
0
10

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Threat Intelligence

EPSS
0.33% (25th percentile)

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  • Snyk IDSNYK-DEBIANUNSTABLE-CPPHTTPLIB-17099877
  • published30 May 2026
  • disclosed29 May 2026

Introduced: 29 May 2026

CVE-2026-45352  (opens in a new tab)
CWE-20  (opens in a new tab)
CWE-770  (opens in a new tab)
CWE-1285  (opens in a new tab)

How to fix?

There is no fixed version for Debian:unstable cpp-httplib.

NVD Description

Note: Versions mentioned in the description apply only to the upstream cpp-httplib package and not the cpp-httplib package as distributed by Debian. See How to fix? for Debian:unstable relevant fixed versions and status.

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.

CVSS Base Scores

version 3.1