Vulnerability Description
An integer underflow vulnerability was found in MIT krb5 in the berval2tl_data() function in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c. The function performs an unsigned subtraction (bv_len - 2) without a prior bounds check. When bv_len is 0 or 1, the subtraction wraps to a large value which is then truncated to uint16_t, yielding 0xFFFE (65534) or 0xFFFF (65535). The subsequent malloc succeeds and memcpy reads up to 65534 bytes from a 0-1 byte buffer, resulting in a heap out-of-bounds read. The attack vector involves a malicious or compromised LDAP KDB backend returning a krbExtraData attribute with bv_len < 2, triggering the underflow when the KDC or kadmind reads principal data.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://access.redhat.com/errata/RHSA-2026:25520
- https://access.redhat.com/security/cve/CVE-2026-11850
- https://bugzilla.redhat.com/show_bug.cgi?id=2459970
FAQ
What is CVE-2026-11850?
CVE-2026-11850 is a vulnerability with a CVSS score of 5.0 (MEDIUM). An integer underflow vulnerability was found in MIT krb5 in the berval2tl_data() function in plugins/kdb/ldap/libkdb_ldap/ldap_principal2.c. The function performs an unsigned subtraction (bv_len - 2) ...
How severe is CVE-2026-11850?
CVE-2026-11850 has been rated MEDIUM with a CVSS base score of 5.0/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-11850?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.