CVE-2026-28435

Payload size limit bypass via gzip decompression in ContentReader (streaming) allows oversized request bodies in cpp-httplib

State: Published
Severity: 7.5 High
Published: Mar 4, 2026
Updated: Mar 4, 2026
Reserved: Feb 27, 2026

Read the record on cve.org

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to 0.35.0, cpp-httplib (httplib.h) does not enforce Server::set_payload_max_length() on the decompressed request body when using HandlerWithContentReader (streaming ContentReader) with Content-Encoding: gzip (or other supported encodings). A small compressed payload can expand beyond the configured payload limit and be processed by the application, enabling a payload size limit bypass and potential denial of service (CPU/memory exhaustion). This vulnerability is fixed in 0.35.0.

Scores

CVSS	Score	Vector	Source
3.1	7.5 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	GitHub_M

Weaknesses

CWE-400 Uncontrolled Resource Consumption
CWE-409 Improper Handling of Highly Compressed Data (Data Amplification)

Affected Products

Product	Versions
cpp-httplibyhirose	< 0.35.0Affected

References

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