What is CVE-2026-22776?

CVE-2026-22776 is a high-severity vulnerability in Yhirose Cpp-Httplib, classified under Improper Handling of Highly Compressed Data (Data Amplification). CVSS score: 7.5/10. Published 2026-01-12.

How severe is CVE-2026-22776?

High severity. CVSS v3 base score is 7.5 out of 10.

Vulnerability in Yhirose Cpp-Httplib

CVE-2026-22776

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. Prior to version 0.30.1, a Denial of Service (DoS) vulnerability exists in cpp-httplib due to the unsafe handling of compressed HTTP request bodies (Content-Encoding: gzip, br, etc.). The library validates the payload_max_length against the compressed data size received from the network, but does not limit the size of the decompressed data stored in memory.

Published 2026-01-12 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.004 (34.3th percentile), scored 2026-10-20.

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 34th percentile — 34.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.004 · newest: 0.004 · change: +0.000

Affected products

Yhirose Cpp-Httplib — versions < 0.30.1

Weakness classification (CWE)

CWE-409 — Improper Handling of Highly Compressed Data (Data Amplification)

References

github.com/yhirose/cpp-httplib/security/advisories/GHSA-h934-98h4-j43q (Exploit, Vendor Advisory)
github.com/yhirose/cpp-httplib/commit/2e2e47bab1ae6a853476eecbc4bf279dd1fef792 (Patch)

Frequently asked questions

What is CVE-2026-22776?: CVE-2026-22776 is a high-severity vulnerability in Yhirose Cpp-Httplib, classified under Improper Handling of Highly Compressed Data (Data Amplification). CVSS score: 7.5/10. Published 2026-01-12.
How severe is CVE-2026-22776?: High severity. CVSS v3 base score is 7.5 out of 10.