MIT Kerberos 5 up to 1.22.2 NegoEx Mechanism /etc/gss/mech gss_accept_sec_context null pointer dereference

CVSS Meta Temp Score
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CTI Interest Score
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5.7$0-$5k0.00

Summaryinfo

A vulnerability identified as problematic has been detected in MIT Kerberos 5 up to 1.22.2. Affected by this issue is the function gss_accept_sec_context of the file /etc/gss/mech of the component NegoEx Mechanism Handler. The manipulation leads to null pointer dereference. This vulnerability is documented as CVE-2026-40355. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in MIT Kerberos 5 up to 1.22.2. This issue affects the function gss_accept_sec_context of the file /etc/gss/mech of the component NegoEx Mechanism Handler. The manipulation with an unknown input leads to a null pointer dereference vulnerability. Using CWE to declare the problem leads to CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. Impacted is availability. The summary by CVE is:

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is a NULL pointer dereference if an application calls gss_accept_sec_context() on a system with a NegoEx mechanism registered in /etc/gss/mech. An unauthenticated remote attacker can trigger this, causing the process to terminate in parse_nego_message.

The advisory is shared at web.mit.edu. The identification of this vulnerability is CVE-2026-40355 since 04/11/2026. The exploitation is known to be difficult. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 311064 (Fedora 45 : krb5 (2026-2e9fe57a46)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.22.3 eliminates this vulnerability.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202604-5566), Tenable (311064) and CERT Bund (WID-SEC-2026-1290). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Affected

  • Red Hat Enterprise Linux
  • Fedora Linux
  • SUSE Linux
  • Oracle Linux
  • SUSE openSUSE
  • RESF Rocky Linux
  • IBM MQ
  • MIT Kerberos
  • Debian Linux
  • IBM QRadar SIEM

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.7
VulDB Meta Temp Score: 5.7

VulDB Base Score: 3.7
VulDB Temp Score: 3.6
VulDB Vector: 🔒
VulDB Reliability: 🔍

NVD Base Score: 7.5
NVD Vector: 🔒

CNA Base Score: 5.9
CNA Vector (MITRE): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Null pointer dereference
CWE: CWE-476 / CWE-404
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 311064
Nessus Name: Fedora 45 : krb5 (2026-2e9fe57a46)

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kerberos 5 1.22.3

Timelineinfo

04/11/2026 CVE reserved
04/28/2026 +17 days Advisory disclosed
04/28/2026 +0 days VulDB entry created
07/08/2026 +71 days VulDB entry last update

Sourcesinfo

Vendor: mit.edu

Advisory: web.mit.edu
Status: Confirmed

CVE: CVE-2026-40355 (🔒)
GCVE (CVE): GCVE-0-2026-40355
GCVE (VulDB): GCVE-100-359921
CERT Bund: WID-SEC-2026-1290 - MIT Kerberos: Mehrere Schwachstellen ermöglichen Denial of Service
CNNVD: CNNVD-202604-5566 - MIT Kerberos 代码问题漏洞

Entryinfo

Created: 04/28/2026 07:42
Updated: 07/08/2026 15:55
Changes: 04/28/2026 07:42 (67), 04/29/2026 21:38 (6), 04/30/2026 07:27 (2), 06/20/2026 05:58 (7), 07/08/2026 15:55 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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