USN-8585-1: Kerberos vulnerabilities

unknownCVE-2026-11850 CVE-2026-40355 CVE-2026-40356

It was discovered that Kerberos had an integer underflow vulnerability in the berval2tl_data() function. An attacker could possibly use this issue to cause Kerberos to crash, resulting in a denial of service. (CVE-2026-11850) It was discovered that Kerberos had vulnerabilities in its NegoEx mechanism parsing. A remote attacker could possibly use these issues to cause Kerberos to crash, resulting in a denial of service. (CVE-2026-40355, CVE-2026-40356)

CSIRTS triage

product: Kerberos Denial of service

What: Kerberos has vulnerabilities that could allow an attacker to cause it to crash, resulting in a denial of service.
Who is affected: Deployments of Kerberos that utilize the affected functions.
Urgency: Remediation is necessary to prevent potential denial of service attacks.
Action: Update to the latest version of Kerberos.

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: 2026-07-22
Exploitation: Not in CISA KEV at last sync

Original advisory: https://ubuntu.com/security/notices/USN-8585-1

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.

Low exploitation riskCVE-2026-118500.26% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 18% of all scored CVEs.
Low exploitation riskCVE-2026-403550.61% 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-2026-403560.60% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 46% of all scored CVEs.

Referenced CVEs

CVE	CSIRTS overview	External
CVE-2026-11850	coverage & exploitation status	NVD · CVE.org
CVE-2026-40355	coverage & exploitation status	NVD · CVE.org
CVE-2026-40356	coverage & exploitation status	NVD · CVE.org

Same CVEs, other sources

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

unknownexploitedSiemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFPcisa
medium[UPDATE] [medium] MIT Kerberos: Multiple vulnerabilities allow denial of servicecert-bund
medium[UPDATE] [medium] MIT Kerberos: Vulnerability allows unspecified attackcert-bund