Vulnerability-Lookup

GHSA-WFQV-66VQ-46RM

Vulnerability from github – Published: 2026-02-19 22:09 – Updated: 2026-02-20 16:43

Summary

Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped

Details

Summary

When verifying artifact signatures using a certificate, Cosign first verifies the certificate chain using the leaf certificate's "not before" timestamp and later checks expiry of the leaf certificate using either a signed timestamp provided by the Rekor transparency log or from a timestamp authority, or using the current time. The root and all issuing certificates are assumed to be valid during the leaf certificate's validity. An issuing certificate with a validity that expires before the leaf certificate will be considered valid during verification even if the provided timestamp would mean the issuing certificate should be considered expired.

Impact

No impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. In practice, this is unlikely to occur as CAs should not be issuing certificates that outlive the validity of the CA and its parents.

Workarounds

Upgrade to the latest release, or verify the certificate chain out of band.

Example to Reproduce

Root CA certificate is valid from 12pm-2pm
Intermediate CA certificate is valid from 12:30pm-1:30pm
Leaf certificate is valid from 1pm-3pm - Note that this is unlikely to happen in practice, as a CA shouldn't issue a certificate that would be valid after the issuing CA certificate expires
Signature generated at 2:30pm with a signed timestamp
During verification, the leaf certificate's not before time (1pm) is used to verify the chain - 1pm is in the validity windows for the root and intermediate CA certificates
The timestamp's time is checked to be in the validity window of only the leaf certificate - 2:30pm is in the validity window for the leaf
Even though the root and intermediate would be expired at 2:30pm, verification succeeds

Severity ?

3.7 (Low)


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

Show details on source website

JSON

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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 3.0.4"
      },
      "package": {
        "ecosystem": "Go",
        "name": "github.com/sigstore/cosign"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "3.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-24122"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-295"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-02-19T22:09:12Z",
    "nvd_published_at": "2026-02-19T23:16:24Z",
    "severity": "LOW"
  },
  "details": "## Summary\n\nWhen verifying artifact signatures using a certificate, Cosign first verifies the certificate chain using the leaf certificate\u0027s \"not before\" timestamp and later checks expiry of the leaf certificate using either a signed timestamp provided by the Rekor transparency log or from a timestamp authority, or using the current time. The root and all issuing certificates are assumed to be valid during the leaf certificate\u0027s validity. An issuing certificate with a validity that expires before the leaf certificate will be considered valid during verification even if the provided timestamp would mean the issuing certificate should be considered expired.\n\n## Impact\n\nNo impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. In practice, this is unlikely to occur as CAs should not be issuing certificates that outlive the validity of the CA and its parents.\n\n## Workarounds\n\nUpgrade to the latest release, or verify the certificate chain out of band.\n\n## Example to Reproduce\n\n* Root CA certificate is valid from 12pm-2pm\n* Intermediate CA certificate is valid from 12:30pm-1:30pm\n* Leaf certificate is valid from 1pm-3pm - **Note that this is unlikely to happen in practice**, as a CA shouldn\u0027t issue a certificate that would be valid after the issuing CA certificate expires\n* Signature generated at 2:30pm with a signed timestamp\n* During verification, the leaf certificate\u0027s not before time (1pm) is used to verify the chain - 1pm is in the validity windows for the root and intermediate CA certificates\n* The timestamp\u0027s time is checked to be in the validity window of only the leaf certificate - 2:30pm is in the validity window for the leaf\n* Even though the root and intermediate would be expired at 2:30pm, verification succeeds",
  "id": "GHSA-wfqv-66vq-46rm",
  "modified": "2026-02-20T16:43:55Z",
  "published": "2026-02-19T22:09:12Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/cosign/security/advisories/GHSA-wfqv-66vq-46rm"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-24122"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/cosign/commit/3c9a7363f563db76d78e2de2cabd945450f3781e"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/sigstore/cosign"
    },
    {
      "type": "WEB",
      "url": "https://github.com/sigstore/cosign/releases/tag/v3.0.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped"
}

CVE-2026-24122 (GCVE-0-2026-24122)

Vulnerability from cvelistv5 – Published: 2026-02-19 22:27 – Updated: 2026-02-20 15:41

Title

Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked

Summary

Cosign provides code signing and transparency for containers and binaries. In versions 3.0.4 and below, an issuing certificate with a validity that expires before the leaf certificate will be considered valid during verification even if the provided timestamp would mean the issuing certificate should be considered expired. When verifying artifact signatures using a certificate, Cosign first verifies the certificate chain using the leaf certificate's "not before" timestamp and later checks expiry of the leaf certificate using either a signed timestamp provided by the Rekor transparency log or from a timestamp authority, or using the current time. The root and all issuing certificates are assumed to be valid during the leaf certificate's validity. There is no impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. This issue has been fixed in version 3.0.5.

Severity ?

3.7 (Low)


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

CWE

CWE-295 - Improper Certificate Validation

Assigner

GitHub_M

References

URL

Tags

	https://github.com/sigstore/cosign/security/advis…	x_refsource_CONFIRM
	https://github.com/sigstore/cosign/commit/3c9a736…	x_refsource_MISC
	https://github.com/sigstore/cosign/releases/tag/v3.0.5	x_refsource_MISC

Impacted products

	Vendor	Product	Version
	sigstore	cosign	Affected: < 3.0.5

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-24122",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-02-20T15:27:28.783661Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-02-20T15:41:03.939Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "cosign",
          "vendor": "sigstore",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 3.0.5"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "Cosign provides code signing and transparency for containers and binaries. In versions 3.0.4 and below, an issuing certificate with a validity that expires before the leaf certificate will be considered valid during verification even if the provided timestamp would mean the issuing certificate should be considered expired. When verifying artifact signatures using a certificate, Cosign first verifies the certificate chain using the leaf certificate\u0027s \"not before\" timestamp and later checks expiry of the leaf certificate using either a signed timestamp provided by the Rekor transparency log or from a timestamp authority, or using the current time. The root and all issuing certificates are assumed to be valid during the leaf certificate\u0027s validity. There is no impact to users of the public Sigstore infrastructure. This may affect private deployments with customized PKIs. This issue has been fixed in version 3.0.5."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "HIGH",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 3.7,
            "baseSeverity": "LOW",
            "confidentialityImpact": "NONE",
            "integrityImpact": "LOW",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-295",
              "description": "CWE-295: Improper Certificate Validation",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-02-19T22:27:08.828Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/sigstore/cosign/security/advisories/GHSA-wfqv-66vq-46rm",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/sigstore/cosign/security/advisories/GHSA-wfqv-66vq-46rm"
        },
        {
          "name": "https://github.com/sigstore/cosign/commit/3c9a7363f563db76d78e2de2cabd945450f3781e",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sigstore/cosign/commit/3c9a7363f563db76d78e2de2cabd945450f3781e"
        },
        {
          "name": "https://github.com/sigstore/cosign/releases/tag/v3.0.5",
          "tags": [
            "x_refsource_MISC"
          ],
          "url": "https://github.com/sigstore/cosign/releases/tag/v3.0.5"
        }
      ],
      "source": {
        "advisory": "GHSA-wfqv-66vq-46rm",
        "discovery": "UNKNOWN"
      },
      "title": "Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-24122",
    "datePublished": "2026-02-19T22:27:08.828Z",
    "dateReserved": "2026-01-21T18:38:22.473Z",
    "dateUpdated": "2026-02-20T15:41:03.939Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-WFQV-66VQ-46RM

Summary

Impact

Workarounds

Example to Reproduce

CVE-2026-24122 (GCVE-0-2026-24122)

Tags

Sightings

Nomenclature