Back Linuxsecurity Ubuntu GnuTLS Critical Denial of Service and Security Issues 2026-8502
Several security issues were fixed in GnuTLS. Software Description: - gnutls28: GNU TLS library Details: It was discovered that GnuTLS had a timing side-channel when processing malformed ciphertexts in RSA-PSK ClientKeyExchange. A remote attacker could possibly use this issue to recover sensitive information. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-0553) Bing Shi discovered that GnuTLS incorrectly handled decoding certain DER-encoded certificates. A remote attacker could possibly use this issue to cause GnuTLS to consume resources, leading to a denial of service. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-12243) Luigino Camastra discovered that GnuTLS incorrectly handled certain PKCS11 token labels. A remote attacker could use this issue to cause GnuTLS to crash, resulting in a denial of service, or possibly execute arbitrary code. The default compiler options for affected releases should reduce the vulnerability to a denial of service. (CVE-2025-9820) ... Read the Full Advisory
Several security issues were fixed in GnuTLS.
Software Description:
- gnutls28: GNU TLS library
It was discovered that GnuTLS had a timing side-channel when processing
malformed ciphertexts in RSA-PSK ClientKeyExchange. A remote attacker
could possibly use this issue to recover sensitive information. This
issue only affected Ubuntu 18.04 LTS. (CVE-2024-0553)
Bing Shi discovered that GnuTLS incorrectly handled decoding certain
DER-encoded certificates. A remote attacker could possibly use this
issue to cause GnuTLS to consume resources, leading to a denial of
service. This issue only affected Ubuntu 18.04 LTS. (CVE-2024-12243)
Luigino Camastra discovered that GnuTLS incorrectly handled certain
PKCS11 token labels. A remote attacker could use this issue to cause
GnuTLS to crash, resulting in a denial of service, or possibly execute
arbitrary code. The default compiler options for affected releases
should reduce the vulnerability to a denial of service. (CVE-2025-9820)
The problem can be corrected by updating your system to the following package versions: Ubuntu 20.04 LTS gnutls-bin 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro guile-gnutls 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro libgnutls-dane0 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro libgnutls-openssl27 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro libgnutls28-dev 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro libgnutls30 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro libgnutlsxx28 3.6.13-2ubuntu1.12+esm2 Available with Ubuntu Pro Ubuntu 18.04 LTS gnutls-bin 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro libgnutls-dane0 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro libgnutls-openssl27 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro libgnutls28-dev 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro libgnutls30 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro libgnutlsxx28 3.5.18-1ubuntu1.6+esm3 Available with Ubuntu Pro Ubuntu 16.04 LTS gnutls-bin 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro guile-gnutls 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro libgnutls-dev 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro libgnutls-openssl27 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro libgnutls28-dev 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro libgnutls30 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro libgnutlsxx28 3.4.10-4ubuntu1.9+esm3 Available with Ubuntu Pro In general, a standard system update will make all the necessary changes.
CVE-2024-0553, CVE-2024-12243, CVE-2025-14831, CVE-2025-9820,
CVE-2026-33845, CVE-2026-33846, CVE-2026-3833, CVE-2026-42009,
Ubuntu Security Notice USN-8502-1
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