Integer Underflow Affecting krb5-workstation package, versions <0:1.21.3-8.amzn2023.0.1


Severity

Recommended
0.0
medium
0
10

Based on Amazon Linux security rating.

Threat Intelligence

EPSS
0.26% (18th percentile)

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  • Snyk IDSNYK-AMZN2023-KRB5WORKSTATION-18063002
  • published21 Jul 2026
  • disclosed11 Jun 2026

Introduced: 11 Jun 2026

CVE-2026-11850  (opens in a new tab)
CWE-191  (opens in a new tab)

How to fix?

Upgrade Amazon-Linux:2023 krb5-workstation to version 0:1.21.3-8.amzn2023.0.1 or higher.
This issue was patched in ALAS2023-2026-1939.

NVD Description

Note: Versions mentioned in the description apply only to the upstream krb5-workstation package and not the krb5-workstation package as distributed by Amazon-Linux. See How to fix? for Amazon-Linux:2023 relevant fixed versions and status.

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 Base Scores

version 3.1