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Vulnerability record · CVE-2026-54919 · published 10 July 2026

CVE-2026-54919: Yhirose cpp-httplib improper certificate validation vulnerability

YYhirose · Cpp Httplib

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. In affected Mbed TLS backend versions from 0.31.0 through 0.46.1 and wolfSSL backend versions from 0.33.0 through 0.46.1, when cpp-httplib is built with CPPHTTPLIB_MBEDTLS_SUPPORT or CPPHTTPLIB_WOLFSSL_SUPPORT and a client connects to an IP-literal host with server certificate verification enabled, SSLClient and Client in HTTPS mode skip certificate chain validation and WebSocketClient on the Mbed TLS backend skips verification altogether, allowing a man-in-the-middle attacker positioned to intercept traffic to present a crafted certificate and read or modify the traffic. This issue is fixed in version 0.47.0.

7.4 CVSS 3.1 High EPSS 0.26% · top 83.6% CWE-295 · Improper certificate validation
7.4CVSS 3.1 base score
0.26%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References
14 Jul 2026Last modified by NVD

Description

cpp-httplib is a C++11 single-file header-only cross platform HTTP/HTTPS library. In affected Mbed TLS backend versions from 0.31.0 through 0.46.1 and wolfSSL backend versions from 0.33.0 through 0.46.1, when cpp-httplib is built with CPPHTTPLIB_MBEDTLS_SUPPORT or CPPHTTPLIB_WOLFSSL_SUPPORT and a client connects to an IP-literal host with server certificate verification enabled, SSLClient and Client in HTTPS mode skip certificate chain validation and WebSocketClient on the Mbed TLS backend skips verification altogether, allowing a man-in-the-middle attacker positioned to intercept traffic to present a crafted certificate and read or modify the traffic. This issue is fixed in version 0.47.0.

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/yhirose/cpp-httplib/commit/fa981cedae004ea9d946f1392b9dec22fac6fee6 Patch
https://github.com/yhirose/cpp-httplib/releases/tag/v0.47.0 ProductRelease Notes
https://github.com/yhirose/cpp-httplib/security/advisories/GHSA-8ffh-4p95-g3p2 MitigationPatchVendor Advisory

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Source: NIST National Vulnerability Database (record CVE-2026-54919), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.