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.
Fix
Nothing published yet: no patch, vendor advisory or mitigation reference on NVD, no vendor advisory in the News for this CVE, not in CISA's KEV, no fixed package version. BaselineWatch does not guess at one.
Change history 1
- First seenCVSS 5.0 · red hatNVD modified 2026-10-31 15:50
Affected (CPE criteria) 0
NVD has not attached CPE configurations yet.
References 3
- https://access.redhat.com/errata/RHSA-2026:25520 vendor-advisory, x_refsource_redhat
- https://access.redhat.com/security/cve/CVE-2026-11850 vdb-entry, x_refsource_redhat
- https://bugzilla.redhat.com/show_bug.cgi?id=2459970 issue-tracking, x_refsource_redhat