Reference page — cumulative record through Monday, October 19, 2026 UTC. Reference pages update as the archive grows; only dated daily editions are immutable pages of record.

CVE-2026-40355

CVE-2026-40355HIGH

MIT Kerberos 5 — 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 sys…

  AV  AC  PR  UI  S  C  I  A   CVSS    EPSS   %ile   KEV
   N   L   N   N  U  N  N  H    7.5   .0085   57.3     —

AFFECTED
  Product     Versions  Fixed
  Kerberos 5  1.18 –    —

TIMELINE
  Apr 11  Reserved by mitre
  Apr 28  Published (CNA: mitre)
  Oct 15  EXPLOIT PUBLISHED — CVE-2026-40355 (MIT Kerberos 5). Public exploit reference added.
  Oct 15  RESCORED — CVE-2026-40355 (MIT Kerberos 5). CVSS 5.9 → 7.5 (NVD).

CWE-476 · CNA: mitre · CVSS v3.1 · 6 references · NVD status: Modified

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.

Lifecycle

Complete event history — 4 events, chronological
Date	Event	Detail
April 11, 2026	Reserved	Reserved by mitre
April 28, 2026	Published	Published (CNA: mitre)
October 15, 2026	EXPLOIT PUBLISHED	EXPLOIT PUBLISHED — CVE-2026-40355 (MIT Kerberos 5). Public exploit reference added.
October 15, 2026	RESCORED	RESCORED — CVE-2026-40355 (MIT Kerberos 5). CVSS 5.9 → 7.5 (NVD).

Affected

Affected products and packages — 1 row
Vendor	Product / Package	Ecosystem	Version introduced	Fixed
MIT	Kerberos 5	—	1.18	—

Weaknesses

CWE-476

References (6)

https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html [Exploit, Patch, Third Party Advisory]
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
https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f [Patch]
https://web.mit.edu/kerberos/advisories/ [Vendor Advisory]

Authoritative record: CVE-2026-40355 at cve.org

Vendors: mit

Weaknesses: CWE-476

About this page

This is a reference page, not a dated page of record. It assembles the complete lifecycle of CVE-2026-40355 from the CVE Program record, NVD enrichment, the CISA KEV catalog, EPSS, and OSV advisories. The box score's numbers (CVSS, EPSS, KEV status) are current as of Monday, October 19, 2026 UTC and are re-derived as the archive grows; only dated daily editions are immutable pages of record. The authoritative source for this identifier is cve.org.