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[USN-9075-1] libjwt vulnerability

Posted on 13 November 2026
Ubuntu Security

==========================================================================Ubuntu Security Notice USN-9075-1
November 12, 2026

libjwt vulnerability
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 22.04 LTS
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

libjwt could be made to accept forged tokens.

Software Description:
- libjwt: C library to handle JWT (JSON Web Token)

Details:

It was discovered that libjwt did not use a constant-time comparison when
verifying HMAC signatures. A remote attacker could possibly use this issue
to forge signatures through a timing side-channel attack and bypass
authentication.

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 22.04 LTS
libjwt-gnutls0 1.10.2-1ubuntu0.22.04.1~esm1
Available with Ubuntu Pro
libjwt0 1.10.2-1ubuntu0.22.04.1~esm1
Available with Ubuntu Pro

Ubuntu 20.04 LTS
libjwt-gnutls0 1.10.2-1ubuntu0.20.04.1~esm1
Available with Ubuntu Pro
libjwt0 1.10.2-1ubuntu0.20.04.1~esm1
Available with Ubuntu Pro

Ubuntu 18.04 LTS
libjwt0 1.9.0-1ubuntu0.1~esm1
Available with Ubuntu Pro

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-9075-1
CVE-2024-25189

--===============8556347075848235545==Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: OpenPGP digital signature

 

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