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Δ / VULNERABILITY RECORD

CVE-2026-40356.

Source-reported disclosure and enrichment record.

SEVERITY / CVSSMEDIUM / 5.9No severity score in this snapshot.
EXPLOITATION STATUSNot listed in the cached KEV catalogThis does not establish absence of exploitation.
RECORD STATUSMicrosoft vendor recordModified Sep 24, 2026

Disclosure summary

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read 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, possibly causing the process to terminate in parse_message.

Source-reported weakness categories

CWE-191

Source-specific records & product guidance

Sources retain their own attribution and scoring. Follow the original record to confirm affected versions, fixed releases, and configuration conditions.

Microsoft Security Updates (CVRF) · 2026-Apr

Open original source · Updated Sep 24, 2026

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read 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, possibly causing the process to terminate in parse_message.

Maximum of vendor-reported product scores; products and fixed builds are associations, not a universal affected-version statement.

Microsoft maximum product score: 5.9

VendorProduct / associationVersion / bounds
Microsoft update guideazl3 krb5 1.21.3-3 on Azure Linux 3.0 (MSRC status code 3)
Microsoft update guidecbl2 krb5 1.19.4-5 on CBL Mariner 2.0 (MSRC status code 3)
Microsoft update guideazl3 krb5 1.21.3-4 on Azure Linux 3.0 (MSRC status code 3)
Microsoft update guidecbl2 krb5 1.19.4-5 on CBL-Mariner 2.0 (MSRC status code 3)

Vendor remediation references

  • CBL-Mariner Releases · build 1.21.3-4 · product IDs 20902-17084, 21405-17084
  • Vendor guidance · product IDs 20902-17084, 21405-17084
  • Release Notes · product IDs 20903-21692
  • Vendor guidance · product IDs 20903-21692

Original records & references

PUBLISHED 2026-04-30T21:03:54-04:00
MODIFIED 2026-09-24T22:36:20-04:00
INGESTED 2026-10-08T12:45:03-04:00