CVE-2026-11850: MIT krb5 · Integer Underflow Vulnerability Was Found
Affects krb5Source GCVE Database
Not known to be exploited · CVSS 5.0 Medium · fixed in 1.19.2-2ubuntu0.8 : update krb5 when convenient.
Data as of 26 Oct 2026, 14:05 UTC
- EPSS
- 0.2% chance of exploitation in 30 days – higher than 19% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 1.19.2-2ubuntu0.8, 1.20.1-6ubuntu2.7, 1.22.1-2ubuntu4.1
CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:L/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 11 Jun 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade the Ubuntu krb5 to 1.19.2-2ubuntu0.8 (package) or 1.20.1-6ubuntu2.7 (package) or 1.22.1-2ubuntu4.1 (package).
Patches and advisories
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSkrb5pkg:deb/ubuntu/krb5?arch=source&distro=resoluteOther threats | Affected
| Fixed in
|
Ubuntu 25.10krb5pkg:deb/ubuntu/krb5?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 24.04 LTSkrb5pkg:deb/ubuntu/krb5?arch=source&distro=nobleOther threats | Affected
| Fixed in
|
Ubuntu 22.04 LTSkrb5pkg:deb/ubuntu/krb5?arch=source&distro=jammyOther threats | Affected
| Fixed in
|
Ubuntu 20.04 LTSkrb5pkg:deb/ubuntu/krb5?arch=source&distro=focalOther threats | Affected
| Fixed in– |
Ubuntu Pro 18.04 LTSkrb5pkg:deb/ubuntu/krb5?arch=source&distro=esm-infra/bionicOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
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.