CVE-2026-11850
Published: June 12, 2026Last modified: June 17, 2026
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.
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score | 5 |
| Attack Vector | NETWORK |
| Attack complexity | HIGH |
| Privileges required | HIGH |
| User interaction | NONE |
| Scope | UNCHANGED |
| Confidentiality | LOW |
| Integrity impact | NONE |
| Availability impact | HIGH |
| Vector | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H |
Status
| Product | Release | Package | Status |
|---|---|---|---|
| Alpaquita Linux | 23 LTS | krb5 | Fixed (1.20.2-r4) |
| 25 LTS | krb5 | Fixed (1.21.3-r3) | |
| Stream | krb5 | Fixed (1.22.2-r3) |