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

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.

Problem type

Affected products

yhirose

cpp-httplib

< 0.35.0 - AFFECTED

References

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xvfx-w463-6fpp

https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-xvfx-w463-6fpp

x_refsource_CONFIRM

https://github.com/yhirose/cpp-httplib/commit/c99d7472b5cf4869d3897b9afc9792063a3d15a8

https://github.com/yhirose/cpp-httplib/commit/c99d7472b5cf4869d3897b9afc9792063a3d15a8

x_refsource_MISC

JSON source

https://cveawg.mitre.org/api/cve/CVE-2026-28435

Click to expand

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