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  4. CVE 2026 11850 krb5 krb5 integer underflow in berval2tldata
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Back to active CVEs
Medium · CVSS 5.0CVE-2026-11850

Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds readCVE-2026-11850

Answer in brief

CVE-2026-11850 records a Medium severity (CVSS 5.0) vulnerability in Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds read. The current sources do not mark it as known exploited. The current feed maps Red Hat/krb5 (generic), Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Jun 11, 2026Updated Aug 31, 2026Source checked Oct 6, 2026First seen by HOL Aug 21, 2026Material review Aug 31, 2026
Upstream Advisory

Key facts

Risk
Medium · CVSS 5.0
Exploitation
Not marked as known exploited
Affected software
3 mapped packages or products
Fix availability
Not reported

Why this deserves its current priority

CVSS is 5.0. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Red Hat/krb5 (generic), Red Hat/openshift/ose-rhel-coreos-8 (generic), Red Hat/openshift/ose-rhel-coreos-9 (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Red Hat/krb5generic*Not reported
Red Hat/openshift/ose-rhel-coreos-8generic*Not reported
Red Hat/openshift/ose-rhel-coreos-9generic*Not reported

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Red Hat/krb5, Red Hat/openshift/ose-rhel-coreos-8, Red Hat/openshift/ose-rhel-coreos-9.
  2. 2Review the reported fix. Source-reported workaround: Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.

Evidence timeline and material changes

  1. Published upstream

    Jun 11, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Aug 31, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 21, 2026

Sources and claim methodology

  • Source referenceaccess.redhat.com
  • Source referenceaccess.redhat.com
  • Source referencebugzilla.redhat.com
Upstream source 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.

Quoted source text, attributed separately from HOL analysis.

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Record context

Vulnerability class
Tool Poisoning
EPSS
Not reported
CWE IDs
CWE-191
Source
CVE List V5
Source checked
Oct 6, 2026
References
3 linked sources
Open source record