USN-8502-1: GnuTLS vulnerabilities

unknownCVE-2024-0553 CVE-2024-12243 CVE-2025-9820 CVE-2025-14831 CVE-2026-3833 CVE-2026-5260

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) Tim Scheckenbach discovered that GnuTLS incorrectly handled malicious certificates containing a large number of name constraints and subject alternative names. A remote attacker could possibly use this issue to cause GnuTLS to consume resources, resulting in a denial of service. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2025-14831) 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 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. This issue only affected Ubuntu 18.04 LTS and Ubuntu 20.04 LTS. (CVE-2026-5260) 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 ob

CSIRTS triage

vendor: GnuTLS product: GnuTLS Information disclosure Denial of service Remote code executionaffected: only affected Ubuntu 18.04 LTS

What: Multiple vulnerabilities could lead to information disclosure, denial of service, or arbitrary code execution.
Who is affected: Users of GnuTLS on Ubuntu 18.04 LTS.
Urgency: Remediation is important due to the severity of the vulnerabilities.
Action: Apply the latest security updates for GnuTLS.

AI-assisted analysis generated from the source advisory — verify against the original.

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Details

Source: Ubuntu Security Notices (INTL · vendor-psirt · site)
Severity: unknown
Published: 2026-07-06
Exploitation: Not in CISA KEV at last sync

Original advisory: https://ubuntu.com/security/notices/USN-8502-1

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

Moderate exploitation riskCVE-2024-05531.6% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 73% of all scored CVEs.
Moderate exploitation riskCVE-2024-122431.2% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 66% of all scored CVEs.
Low exploitation riskCVE-2025-98200.20% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 10% of all scored CVEs.
Low exploitation riskCVE-2025-148310.64% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 46% of all scored CVEs.
Low exploitation riskCVE-2026-38330.57% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 43% of all scored CVEs.
Low exploitation riskCVE-2026-52600.73% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 50% of all scored CVEs.
Low exploitation riskCVE-2026-338450.80% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 52% of all scored CVEs.
Moderate exploitation riskCVE-2026-338461.3% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 66% of all scored CVEs.
Moderate exploitation riskCVE-2026-420091.3% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 68% of all scored CVEs.
Moderate exploitation riskCVE-2026-420101.1% 30-day exploitation probability. Patch within normal cadence, watch for KEV listing. Riskier than 60% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2024-0553	coverage & exploitation status	NVD · CVE.org
CVE-2024-12243	coverage & exploitation status	NVD · CVE.org
CVE-2025-9820	coverage & exploitation status	NVD · CVE.org
CVE-2025-14831	coverage & exploitation status	NVD · CVE.org
CVE-2026-3833	coverage & exploitation status	NVD · CVE.org
CVE-2026-5260	coverage & exploitation status	NVD · CVE.org
CVE-2026-33845	coverage & exploitation status	NVD · CVE.org
CVE-2026-33846	coverage & exploitation status	NVD · CVE.org
CVE-2026-42009	coverage & exploitation status	NVD · CVE.org
CVE-2026-42010	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

high[UPDATE] [high] GnuTLS: Multiple vulnerabilitiescert-bund
medium[UPDATE] [medium] GnuTLS: Multiple vulnerabilities allow Denial of Servicecert-bund
medium[UPDATE] [medium] GnuTLS: Vulnerability allows denial of servicecert-bund
medium[UPDATE] [medium] GnuTLS: Multiple vulnerabilitiescert-bund
low[UPDATE] [low] GnuTLS: Vulnerability allows unspecified attackcert-bund