CVE-2026-107708
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.
Does this matter?
Lower severity and a low EPSS score (0.52%). Track it; it rarely justifies an emergency change on its own.
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.
- CVSS 4.0
- 6.9 MEDIUMCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M
- EPSS
- 0.52% probability · 44th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-476
- Source
- disclosure@vulncheck.com
EPSS moved from 0.5% on 9 October 2026 to 0.5% on 26 October 2026.
References
- https://github.com/krb5/krb5
- https://github.com/krb5/krb5/blob/krb5-1.22.2-final/src/kdc/kdc_util.c#L639-L676
- https://github.com/krb5/krb5/commit/a88a18cafa1040a0c4f9c8d08288fc98831ec86d
- https://github.com/krb5/krb5/commit/f6e2c397ceda6467ebbaab8ed66d4895c9f1d6a7
- https://github.com/krb5/krb5/pull/1510
- https://www.vulncheck.com/advisories/mit-krb5-through-1.22.2-kdc-null-pointer-dereference-via-s4u2proxy-pac
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.