CVE-2026-45352 (GCVE-0-2026-45352)

Vulnerability from cvelistv5 – Published: 2026-05-29 19:14 – Updated: 2026-06-02 01:52
VLAI
Title
cpp-httplib DoS: Negative chunk-size in chunked Transfer-Encoding
Summary
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.
Severity
5.3 (Medium)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
SSVC
Exploitation: poc Automatable: yes Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-06-02 01:51 UTC
CWE
  • CWE-20 - Improper Input Validation
  • CWE-1285 - Improper Validation of Specified Index, Position, or Offset in Input
  • CWE-770 - Allocation of Resources Without Limits or Throttling
Assigner
References
Impacted products
Vendor Product Version CPE status
yhirose cpp-httplib Affected: < 0.43.4
guessed Create a notification for this product.
Show details on NVD website
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