Krb5: krb5: integer underflow in berval2tl_data() leads to heap out-of-bounds read
Summary
| CVE | CVE-2026-11850 |
|---|---|
| State | PUBLISHED |
| Assigner | redhat |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-06-11 10:16:21 UTC |
| Updated | 2026-10-31 16:17:01 UTC |
| 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. |
Risk And Classification
Primary CVSS: v3.1 5 MEDIUM from [email protected]
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H
EPSS: 0.002710000 probability, percentile 0.193570000 (date 2026-10-31)
Problem Types: CWE-191 | CWE-191 Integer Underflow (Wrap or Wraparound)
| Version | Source | Type | Score | Severity | Vector |
|---|---|---|---|---|---|
| 3.1 | [email protected] | Secondary | 5 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H |
| 3.1 | CNA | CVSS | 5 | MEDIUM | CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H |
CVSS v3.1 Breakdown
Attack Vector
NetworkAttack Complexity
HighPrivileges Required
HighUser Interaction
NoneScope
UnchangedConfidentiality
LowIntegrity
NoneAvailability
HighCVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:H
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Red Hat | Red Hat Hardened Images | unaffected 1.22.2-8.hum1 * rpm | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 10 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 6 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 7 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 8 | Not specified | Not specified |
| CNA | Red Hat | Red Hat Enterprise Linux 9 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 4 | Not specified | Not specified |
| CNA | Red Hat | Red Hat OpenShift Container Platform 5 | Not specified | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.redhat.com/show_bug.cgi | [email protected] | bugzilla.redhat.com | |
| access.redhat.com/security/cve/CVE-2026-11850 | [email protected] | access.redhat.com | |
| access.redhat.com/errata/RHSA-2026:25520 | [email protected] | access.redhat.com | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Red Hat would like to thank Sebastián Alba Vives for reporting this issue. (en)
Additional Advisory Data
| Source | Time | Event |
|---|---|---|
| CNA | 2026-04-21T00:00:00.000Z | Reported to Red Hat. |
| CNA | 2026-06-10T00:00:00.000Z | Made public. |
Workarounds
CNA: 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.
There are currently no legacy QID mappings associated with this CVE.