Is CVE-2025-13034 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2025-13034 being exploited in the wild.

How severe is CVE-2025-13034?

Medium severity, with a CVSS score of 5.9, published 8 January 2026.

Which products and versions are affected?

curl curl 8.8.0 to 8.17.0 (multiple branches patched at 8.14.2, 8.16.1, and 8.18.0).

Is there a fix for CVE-2025-13034?

A patch was published on 2026-01-07: curl 8.18.0 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2025-13034 attacked?

It is attacked over the network.

Am I affected by CVE-2025-13034?

Check whether you run Haxx Curl. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2025-13034: curl certificate pinning bypass in QUIC with GnuTLS

CVE-2025-13034 · Severity: medium · CVSS 5.9 · Published 2026-01-08

curl is a widely-used tool and library for downloading files and making web requests. When configured to pin specific server certificates for security (using the CURLOPT_PINNEDPUBLICKEY option), curl should reject any server presenting a different certificate. However, under specific conditions—using the QUIC protocol with GnuTLS and when certificate verification is disabled—this pinning check is skipped, allowing an attacker to perform a man-in-the-middle attack and impersonate the intended server.

Technologies: Haxx Curl. Vendors: Haxx.

Quick answers

Is CVE-2025-13034 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2025-13034 being exploited in the wild.
How severe is CVE-2025-13034?: Medium severity, with a CVSS score of 5.9, published 8 January 2026.
Which products and versions are affected?: curl curl 8.8.0 to 8.17.0 (multiple branches patched at 8.14.2, 8.16.1, and 8.18.0).
Is there a fix for CVE-2025-13034?: A patch was published on 2026-01-07: curl 8.18.0 released with fix Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2025-13034 attacked?: It is attacked over the network.
Am I affected by CVE-2025-13034?: Check whether you run Haxx Curl. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

This is an improper certificate validation vulnerability (CWE-295) affecting curl's QUIC/HTTP3 implementation when using ngtcp2 with GnuTLS as the TLS backend. When a user sets the CURLOPT_PINNEDPUBLICKEY option (or --pinnedpubkey flag) to pin a server's public key, curl should validate the server certificate against the pinned key before allowing the connection. The vulnerability exists because this validation is skipped when all three conditions are met: (1) QUIC protocol is used, (2) ngtcp2 backend is built with GnuTLS, and (3) standard certificate verification has been explicitly disabled. The attack vector is network-based and requires no user interaction beyond establishing the connection. An attacker in a network position to intercept traffic can present an alternative certificate and be accepted as the legitimate server. Patches are available in curl 8.14.2, 8.16.1, and 8.18.0; versions prior to 8.8.0 are unaffected.

Affected products

curl curl 8.8.0 to 8.17.0 (multiple branches patched at 8.14.2, 8.16.1, and 8.18.0)

Timeline

2026-01-07: disclosed: Security advisory published by curl project
2026-01-07: patched: curl 8.18.0 released with fix
2025-11-09: other: Vulnerability reported to curl project by Stanislav Fort (Aisle Research)

References

This page as Markdown. Free to reuse under CC BY 4.0 with a link back.