What’s Vulnerable › Vulnerabilities

CVE-2026-40355

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.6% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-28 · updated 2026-10-26
• Weakness: CWE-476

Description

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parse_nego_message.

Affected products

• MIT Kerberos 5: from 1.18.0 through 1.22.2

References

• https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
• https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
• https://web.mit.edu/kerberos/advisories/
• https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
• https://cert-portal.siemens.com/productcert/html/ssa-019113.html
• https://cert-portal.siemens.com/productcert/html/ssa-082556.html
• https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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