Home / mailings [USN-8284-1] GnuTLS vulnerabilities
Posted on 20 May 2026
Ubuntu Security==========================================================================Ubuntu Security Notice USN-8284-1
May 20, 2026
gnutls28 vulnerabilities
==========================================================================
A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 26.04 LTS
- Ubuntu 25.10
- Ubuntu 24.04 LTS
- Ubuntu 22.04 LTS
Summary:
Several security issues were fixed in GnuTLS.
Software Description:
- gnutls28: GNU TLS library
Details:
Joshua Rogers discovered that GnuTLS did not properly handle malformed
DTLS handshake fragments in certain cases. A remote attacker could
possibly use this issue to obtain sensitive information, or cause a
denial of service. (CVE-2026-33845)
Haruto Kimura, Oscar Reparaz, and Zou Dikai discovered that GnuTLS did
not properly validate DTLS handshake fragment lengths in certain cases. A
remote attacker could possibly use this issue to cause GnuTLS to crash,
resulting in a denial of service, or execute arbitrary code.
(CVE-2026-33846)
Oleh Konko and Joshua Rogers discovered that GnuTLS did not properly
validate OCSP responses in certain cases. A remote attacker could
possibly use this issue to bypass certificate revocation checks, leading
to a machine-in-the-middle attack. (CVE-2026-3832)
Oleh Konko and Joshua Rogers discovered that GnuTLS did not properly
handle case-insensitive name constraints in certain cases. A remote
attacker could possibly use this issue to bypass certificate validation,
leading to a machine-in-the-middle attack. (CVE-2026-3833)
Joshua Rogers discovered that GnuTLS did not properly order DTLS packets
with duplicate sequence numbers in certain cases. A remote attacker could
possibly use this issue to cause GnuTLS to crash, resulting in a denial
of service. (CVE-2026-42009)
Joshua Rogers discovered that GnuTLS did not properly handle usernames
containing NUL characters in certain RSA-PSK configurations. A remote
attacker could possibly use this issue to bypass authentication and gain
unintended access to services. (CVE-2026-42010)
Haruto Kimura discovered that GnuTLS did not properly apply permitted
name constraints in certain certificate validation paths. A remote
attacker could possibly use this issue to bypass certificate validation,
leading to a machine-in-the-middle attack. (CVE-2026-42011)
Oleh Konko discovered that GnuTLS incorrectly fell back to Common Name
checks for certain URI and SRV subject alternative names. A remote
attacker could possibly use this issue to bypass certificate validation,
leading to a machine-in-the-middle attack. (CVE-2026-42012)
Haruto Kimura and Joshua Rogers discovered that GnuTLS incorrectly fell
back to Common Name checks when subject alternative names were oversized.
A remote attacker could possibly use this issue to bypass certificate
validation, leading to a machine-in-the-middle attack. (CVE-2026-42013)
Luigino Camastra and Joshua Rogers discovered that GnuTLS had a
use-after-free issue when changing PKCS#11 token security officer PINs in
certain cases. An attacker could possibly use this issue to cause GnuTLS
to crash, resulting in a denial of service, or execute arbitrary code.
(CVE-2026-42014)
Zou Dikai discovered that GnuTLS did not properly validate PKCS#12 bag
sizes in certain cases. An attacker could possibly use this issue to
cause GnuTLS to crash, resulting in a denial of service, or execute
arbitrary code. (CVE-2026-42015)
Joshua Rogers discovered that GnuTLS did not properly handle very short
premaster secrets in certain RSA key exchange cases with PKCS#11-backed
server keys. A remote attacker could possibly use this issue to obtain
sensitive information. (CVE-2026-5260)
Doria Tang discovered that GnuTLS did not perform PKCS#7 padding checks
in constant time in certain cases. A remote attacker could possibly use
this issue to obtain sensitive information. This issue only affected
Ubuntu 24.04 LTS, Ubuntu 25.10, and Ubuntu 26.04 LTS. (CVE-2026-5419)
Update instructions:
The problem can be corrected by updating your system to the following
package versions:
Ubuntu 26.04 LTS
libgnutls30t64 3.8.12-2ubuntu1.1
Ubuntu 25.10
libgnutls30t64 3.8.9-3ubuntu2.2
Ubuntu 24.04 LTS
libgnutls30t64 3.8.3-1.1ubuntu3.6
Ubuntu 22.04 LTS
libgnutls30 3.7.3-4ubuntu1.9
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-8284-1
CVE-2026-33845, CVE-2026-33846, CVE-2026-3832, CVE-2026-3833,
CVE-2026-42009, CVE-2026-42010, CVE-2026-42011, CVE-2026-42012,
CVE-2026-42013, CVE-2026-42014, CVE-2026-42015, CVE-2026-5260,
CVE-2026-5419
Package Information:
https://launchpad.net/ubuntu/+source/gnutls28/3.8.12-2ubuntu1.1
https://launchpad.net/ubuntu/+source/gnutls28/3.8.9-3ubuntu2.2
https://launchpad.net/ubuntu/+source/gnutls28/3.8.3-1.1ubuntu3.6
https://launchpad.net/ubuntu/+source/gnutls28/3.7.3-4ubuntu1.9
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