# CVE-2026-45352

## Summary

- **CVE ID:** CVE-2026-45352
- **Severity:** MEDIUM
- **CVSS Score:** 5.3 (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L)
- **CWE:** CWE-20, CWE-1285, CWE-770
- **Published:** May 29, 2026
- **Last Modified:** Jun 2, 2026

## Description

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.

## Affected Products

- yhirose — cpp-httplib (< 0.43.4)

## References

- [CNA](https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-h6wq-j5mv-f3q8)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.33%
- **EPSS Percentile:** 25.5

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-09._