CVE-2025-13034: No QUIC certificate pinning with GnuTLS

Severity: medium (CVSS 5.9 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-01-08 · updated 2026-09-15
Weakness: CWE-295

Description

When using `CURLOPT_PINNEDPUBLICKEY` option with libcurl or `--pinnedpubkey` with the curl tool, curl should check the public key of the server certificate to verify the peer. This check was skipped in a certain condition that would then make curl allow the connection without performing the proper check, thus not noticing a possible impostor. To skip this check, the connection had to be done with QUIC with ngtcp2 built to use GnuTLS and the user had to explicitly disable the standard certificate verification.

Affected products

curl: from 8.8.0 before 8.18.0 — fixed in 8.18.0

How to fix

Upgrade to a fixed version: curl 8.18.0. Check the vendor advisory for mitigations.

References

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