Vulnerability-Lookup

OESA-2026-2257 (CVE-2026-40355)

Vulnerability from osv_openeuler – Published: 2026-05-09 11:11 – Updated: 2026-08-06 11:11 – Source website

Summary

krb5 security update

Details

Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography.

Security Fix(es):

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.(CVE-2026-40355)

In MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read 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, possibly causing the process to terminate in parse_message.(CVE-2026-40356)

Severity

5.9 (Medium)


                    
                      CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

References

URL

Type

	https://www.openeuler.org/zh/security/security-bu…	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-40355	ADVISORY
	https://nvd.nist.gov/vuln/detail/CVE-2026-40356	ADVISORY

JSON

To clipboard

{
  "affected": [
    {
      "ecosystem_specific": {
        "aarch64": [
          "krb5-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-client-1.21.2-20.oe2403sp1.aarch64.rpm",
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          "krb5-debugsource-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-server-1.21.2-20.oe2403sp1.aarch64.rpm"
        ],
        "noarch": [
          "krb5-help-1.21.2-20.oe2403sp1.noarch.rpm"
        ],
        "src": [
          "krb5-1.21.2-20.oe2403sp1.src.rpm"
        ],
        "x86_64": [
          "krb5-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-client-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-server-1.21.2-20.oe2403sp1.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS-SP1",
        "name": "krb5",
        "purl": "pkg:rpm/openEuler/krb5\u0026distro=openEuler-24.03-LTS-SP1"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.21.2-20.oe2403sp1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
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          "krb5-client-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp3.aarch64.rpm",
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        ],
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        ],
        "src": [
          "krb5-1.21.2-20.oe2403sp3.src.rpm"
        ],
        "x86_64": [
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          "krb5-client-1.21.2-20.oe2403sp3.x86_64.rpm",
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          "krb5-server-1.21.2-20.oe2403sp3.x86_64.rpm"
        ]
      },
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        "name": "krb5",
        "purl": "pkg:rpm/openEuler/krb5\u0026distro=openEuler-24.03-LTS-SP3"
      },
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            },
            {
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          "krb5-debugsource-1.18.2-23.oe2003sp4.aarch64.rpm",
          "krb5-devel-1.18.2-23.oe2003sp4.aarch64.rpm",
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        ],
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          "krb5-debuginfo-1.18.2-23.oe2003sp4.x86_64.rpm",
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          "krb5-devel-1.18.2-23.oe2003sp4.x86_64.rpm",
          "krb5-libs-1.18.2-23.oe2003sp4.x86_64.rpm",
          "krb5-server-1.18.2-23.oe2003sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:20.03-LTS-SP4",
        "name": "krb5",
        "purl": "pkg:rpm/openEuler/krb5\u0026distro=openEuler-20.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.2-23.oe2003sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "krb5-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-client-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-debuginfo-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-debugsource-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-devel-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-libs-1.19.2-30.oe2203sp4.aarch64.rpm",
          "krb5-server-1.19.2-30.oe2203sp4.aarch64.rpm"
        ],
        "noarch": [
          "krb5-help-1.19.2-30.oe2203sp4.noarch.rpm"
        ],
        "src": [
          "krb5-1.19.2-30.oe2203sp4.src.rpm"
        ],
        "x86_64": [
          "krb5-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-client-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-debuginfo-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-debugsource-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-devel-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-libs-1.19.2-30.oe2203sp4.x86_64.rpm",
          "krb5-server-1.19.2-30.oe2203sp4.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:22.03-LTS-SP4",
        "name": "krb5",
        "purl": "pkg:rpm/openEuler/krb5\u0026distro=openEuler-22.03-LTS-SP4"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.19.2-30.oe2203sp4"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "aarch64": [
          "krb5-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-client-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-server-1.21.2-20.oe2403sp1.aarch64.rpm",
          "krb5-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-client-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-server-1.21.2-20.oe2403sp3.aarch64.rpm",
          "krb5-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-client-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-devel-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-libs-1.21.2-20.oe2403.aarch64.rpm",
          "krb5-server-1.21.2-20.oe2403.aarch64.rpm"
        ],
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          "krb5-help-1.21.2-20.oe2403sp3.noarch.rpm",
          "krb5-help-1.21.2-20.oe2403.noarch.rpm"
        ],
        "src": [
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          "krb5-1.21.2-20.oe2403sp3.src.rpm",
          "krb5-1.21.2-20.oe2403.src.rpm"
        ],
        "x86_64": [
          "krb5-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-client-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-server-1.21.2-20.oe2403sp1.x86_64.rpm",
          "krb5-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-client-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-devel-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-libs-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-server-1.21.2-20.oe2403sp3.x86_64.rpm",
          "krb5-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-client-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-debuginfo-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-debugsource-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-devel-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-libs-1.21.2-20.oe2403.x86_64.rpm",
          "krb5-server-1.21.2-20.oe2403.x86_64.rpm"
        ]
      },
      "package": {
        "ecosystem": "openEuler:24.03-LTS",
        "name": "krb5",
        "purl": "pkg:rpm/openEuler/krb5\u0026distro=openEuler-24.03-LTS"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.21.2-20.oe2403"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "database_specific": {
    "severity": "Medium"
  },
  "details": "Kerberos is a network authentication protocol. It is designed to provide strong authentication for client/server applications by using secret-key cryptography.\r\n\r\nSecurity Fix(es):\n\nIn 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.(CVE-2026-40355)\n\nIn MIT Kerberos 5 (aka krb5) before 1.22.3, there is an integer underflow and resultant out-of-bounds read 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, possibly causing the process to terminate in parse_message.(CVE-2026-40356)",
  "id": "OESA-2026-2257",
  "modified": "2026-08-06T11:11:14Z",
  "published": "2026-05-09T11:11:14Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-2257"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40355"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-40356"
    }
  ],
  "schema_version": "1.7.2",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "krb5 security update",
  "upstream": [
    "CVE-2026-40355",
    "CVE-2026-40356"
  ]
}

CVE-2026-40355 (GCVE-0-2026-40355)

Vulnerability from cvelistv5 – Published: 2026-04-28 00:00 – Updated: 2026-09-08 08:48

Summary

Severity

5.9 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: poc Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-28 12:53 UTC

CWE

CWE-476 - NULL Pointer Dereference

Assigner

mitre mitre root

References

5 references

URL	Tags
https://web.mit.edu/kerberos/advisories/
https://cems.fun/2026/04/27/krb5-two-unauthentica…
https://github.com/krb5/krb5/commit/2e75f0d9362fb…
https://cert-portal.siemens.com/productcert/html/…
https://cert-portal.siemens.com/productcert/html/…

Impacted products

7 products

Vendor	Product	Version
MIT	Kerberos 5	Affected: 1.18 , < 1.22.3 (custom) cpe:2.3:a:mit:kerberos_5::::::::
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.6 , < * (custom)
Siemens	SIPLUS S7-1500 CPU 1518-4 PN/DP MFP	Affected: V3.1.5 , < * (custom)

Show details on NVD website

JSON

To clipboard

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                "id": "CVE-2026-40355",
                "options": [
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CVE-2026-40356 (GCVE-0-2026-40356)

Vulnerability from cvelistv5 – Published: 2026-04-28 00:00 – Updated: 2026-04-28 13:10

Summary

Severity

5.9 (Medium)


                        
                          CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-04-28 13:10 UTC

CWE

CWE-191 - Integer Underflow (Wrap or Wraparound)

Assigner

mitre mitre root

References

3 references

URL	Tags
https://web.mit.edu/kerberos/advisories/
https://cems.fun/2026/04/27/krb5-two-unauthentica…
https://github.com/krb5/krb5/commit/2e75f0d9362fb…

Impacted products

1 product

Vendor	Product	Version
MIT	Kerberos 5	Affected: 1.18 , < 1.22.3 (custom) cpe:2.3:a:mit:kerberos_5::::::::

Show details on NVD website

JSON

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Sightings

Author	Source	Type	Date	Other

Nomenclature

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Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

Action not permitted

OESA-2026-2257 (CVE-2026-40355)

CVE-2026-40355 (GCVE-0-2026-40355)

CVE-2026-40356 (GCVE-0-2026-40356)

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