CVE-2026-45352

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 v3 5.3 MEDIUM

5.3^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 3.9 / Impact : 1.4

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact LOW

Scope UNCHANGED

References

Link	Resource
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8	Exploit Vendor Advisory
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8	Exploit Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:yhirose:cpp-httplib:*:*:*:*:*:*:*:*

History

No history.

Information

Published : 2026-05-29 20:16

Updated : 2026-07-22 06:10

NVD link : CVE-2026-45352

Mitre link : CVE-2026-45352

CVE.ORG link : CVE-2026-45352

JSON object : View

Products Affected

yhirose

cpp-httplib

CWE

CWE-20

Improper Input Validation

CWE-770

Allocation of Resources Without Limits or Throttling

CWE-1285

Improper Validation of Specified Index, Position, or Offset in Input

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