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CVE-2026-40356

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 regis...

Published: Apr 28, 2026Updated: Apr 28, 2026 Sources: CVE List NVD
NVD MITRE
5.9CVSS
MEDIUM

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.

EPSS Score
N/A
CISA KEV
Not in KEV
Exploits
No Known Exploits
Remediation
No Fix Available

CVSS Vector Breakdown

AV:NAC:HPR:NUI:NS:UC:NI:NA:H
Exploitability
AV:NAttack Vector
Network
AC:HAttack Complexity
High
PR:NPrivileges Required
None
UI:NUser Interaction
None
Scope
S:UScope
Unchanged
Impact
C:NConfidentiality
None
I:NIntegrity
None
A:HAvailability
High

Weaknesses

CWE-191

Affected Products

Kerberos 5
MIT

Attack Graph

Products CVE Techniques Tactics

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Exploitability

No known exploits, KEV entries, or remediation guidance available for this vulnerability yet.

MITRE ATT&CK

1 technique
Initial Access
View detailed technique mapping

References

https://web.mit.edu/kerberos/advisories/
web.mit.edu
https://cems.fun/2026/04/27/krb5-two-unauthenticated-network-vulnerabilities.html
cems.fun
https://github.com/krb5/krb5/commit/2e75f0d9362fb979f5fc92829431a590a130929f
github.com

Timeline

Published
Apr 28, 2026
Last Updated
Apr 28, 2026

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