CVE-2026-107708

Name	CVE-2026-107708
Description	MIT krb5 through 1.22.2 contains a NULL pointer dereference vulnerability in the KDC's get_pac_princ_with_realm() that returns success while leaving the client principal NULL on malformed names. A malicious or compromised cross-realm trusted KDC can send an S4U2Proxy request with a PAC carrying a malformed client name to crash krb5kdc and deny authentication.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
krb5 (PTS)	bookworm, bookworm (security)	1.20.1-2+deb12u5	vulnerable
	trixie (security), trixie	1.21.3-5+deb13u1	vulnerable
	forky, sid	1.22.1-3	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
krb5	source	(unstable)	(unfixed)

Notes

https://github.com/krb5/krb5/pull/1510
Fixed by: https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7 (master)
Fixed by: https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d (krb5-1.22 branch)