SB2026010741 - Multiple vulnerabilities in cURL
Published: January 7, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 6 secuirty vulnerabilities.
1) Improper authentication (CVE-ID: CVE-2025-15224)
The vulnerability allows a remote attacker to bypass authentication process.
The vulnerability exists due to an error when doing SSH-based transfers using either SCP or SFTP, and asked to do public key authentication. In such case the curl would wrongly still ask and authenticate using a locally running SSH agent.
Note, the vulnerability affects libcurl builds that use libssh backend instead of libssh2.
2) Improper validation of certificate with host mismatch (CVE-ID: CVE-2025-15079)
The vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists during SSH-based transfers due to the library mistakenly accepts connections to hosts not present in the specified file if they were added as recognized in the libssh global knownhosts file. A remote attacker can perform a MitM attack.
Note, the vulnerability affects libcurl builds that use libssh backend instead of libssh2.
3) Improper Certificate Validation (CVE-ID: CVE-2025-14819)
The vulnerability allows a remote attacker to perform MitM attack.
The vulnerability exists due to the way libcurl handles TLS transfers when using the CURLSSLOPT_NO_PARTIALCHAIN option. A remote attacker can trick the library into re-using a CA store cached in memory for which the partial chain option was reversed, leading to store policy bypass and a potential MitM attack.
4) Insufficiently protected credentials (CVE-ID: CVE-2025-14524)
The vulnerability allows an attacker to obtain bearer token,
The vulnerability exists due to an error when handling cross-protocol redirects. When an oauth2 bearer token is used for an HTTP(S) transfer, and that transfer performs a cross-protocol redirect to a second URL that uses an IMAP, LDAP, POP3 or SMTP scheme, curl might wrongly pass on the bearer token to the new target host.
5) Unsynchronized access to shared data in a multithreaded context (CVE-ID: CVE-2025-14017)
The vulnerability allows an attacker to bypass implemented security restrictions.
The vulnerability exists due to an error when performing multithreaded LDAPS transfers (LDAP over TLS) with libcurl. Changing TLS options in one thread would inadvertently change them globally and therefore possibly also affect other concurrently setup transfers. For example, disabling certificate verification for a specific transfer could unintentionally disable the feature for other threads as well, leading to a MitM attacks against other websites.
6) Protection Mechanism Failure (CVE-ID: CVE-2025-13034)
The vulnerability allows a remote attacker to bypass implemented security restrictions.
The vulnerability exists due to insufficient implementation of security measures. 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 verifiation.
Remediation
Install update from vendor's website.