CVE-2026-107708
MediumCVSS 4.9Exploitation Probability (EPSS)
Low risk42th percentile - higher than 42% of all known CVEs
Summary
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.
Risk Assessment
A malicious or compromised trusted KDC can remotely crash krb5kdc, causing complete unavailability of the Kerberos authentication service in the domain.
Recommendation
Update MIT krb5 to a patched version and verify cross-realm trust, restricting it to verified KDCs only.
Other vulnerabilities in MIT Kerberos 5
See all- CVE-2024-37370High
In MIT Kerberos 5 before version 1.21.3, an attacker can modify the Extra Count field of a confidential GSS krb5 wrap token, causing the unwrapped token to appear truncated to the application.
- CVE-2024-37371Critical
In MIT Kerberos 5 before version 1.21.3, an attacker can cause invalid memory reads during GSS message token handling by sending message tokens with invalid length fields.
- CVE-2026-107778Medium
MIT Kerberos 5 (krb5) through 1.22.2 contains a NULL pointer dereference in make_cred_list() in rd_cred.c that allows authenticated Kerberos clients to crash services by sending mismatched KRB-CRED arrays. Attackers can send forwarded credentials with more tickets than ticket_info entries through gss_accept_sec_context() to crash GSS-API acceptor services, causing denial of service.
- CVE-2026-40356Medium
In MIT Kerberos 5 (krb5) before 1.22.3, an integer underflow and resultant out-of-bounds read occur 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.
- CVE-2026-40355Medium
In MIT Kerberos 5 (krb5) before version 1.22.3, there is a NULL pointer dereference when 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.
- CVE-2025-3576Medium
A vulnerability in the MIT Kerberos implementation allows GSSAPI-protected messages using RC4-HMAC-MD5 to be spoofed due to weaknesses in the MD5 checksum design. If RC4 is preferred over stronger encryption types, an attacker could exploit MD5 collisions to forge message integrity codes.
Original NVD description (English source)
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS