Cosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked
cve-program · CVE-2026-24122
PublishedCosign 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.
Read the publisher's advisoryeuvd · EUVD-2026-8430
PublishedCosign 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.
Read the publisher's advisorynvd · CVE-2026-24122
PublishedCosign 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.
Read the publisher's advisoryosv · GHSA-wfqv-66vq-46rm
Published## 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
Read the publisher's advisoryosv · GO-2026-4529
PublishedCosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped in github.com/sigstore/cosign
Read the publisher's advisoryAffected versions, risk and source history
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cve-program · CVE-2026-24122
PublishedCosign Certificate Chain Expiry Validation Issue Allows Issuing Certificate Expiry to Be Overlooked
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.
- Source published
- 19 Feb 2026 22:27:08 UTC
- Source modified
- 20 Feb 2026 15:41:03 UTC
- Saved here
- 23 Oct 2026 15:48:27 UTC
- Source terms
- CVE Program Terms of Use
Original source record · Cite this exact observation · Complete original publisher JSON
Source: cve-program · CVE Program Terms of Use. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
euvd · EUVD-2026-8430
PublishedCosign 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…
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.
Additional publisher context
EUVD source date text has no stated timezone and is retained without inventing a UTC instant. Related bulletin membership is not an alias, common cause or applicability claim. A missing vector with a zero score is treated as unrated. Complete vendor/product and underlying source evidence remains in the original JSON.
Original publisher date fields
datePublished: Feb 19, 2026, 10:27:08 PM
dateUpdated: Feb 20, 2026, 3:41:03 PM
8 related source bulletins · separate from aliases
openSUSE-SU-2026:11676-1: trivy-0.74.0-2.1 on GA media
CVE-2026-24122 · CVE-2026-37236 · CVE-2026-41178 · CVE-2026-50163
SUSE-SU-2026:20904-1: Security update for cosign
CVE-2025-11065 · CVE-2025-58181 · CVE-2026-22703 · CVE-2026-22772 · CVE-2026-23991 · CVE-2026-23992 · CVE-2026-24122 · CVE-2026-24137 · CVE-2026-26958
SUSE-SU-2026:0777-1: Security update for cosign
CVE-2025-11065 · CVE-2025-58181 · CVE-2026-22703 · CVE-2026-22772 · CVE-2026-23991 · CVE-2026-23992 · CVE-2026-24122 · CVE-2026-24137 · CVE-2026-26958
openSUSE-SU-2026:10635-1: hauler-1.4.2-1.1 on GA media
CVE-2026-24122
openSUSE-SU-2026:20386-1: Security update for cosign
CVE-2025-11065 · CVE-2025-58181 · CVE-2026-22703 · CVE-2026-22772 · CVE-2026-23991 · CVE-2026-23992 · CVE-2026-24122 · CVE-2026-24137 · CVE-2026-26958
openSUSE-SU-2026:10235-1: cosign-3.0.5-1.1 on GA media
CVE-2026-22772 · CVE-2026-23991 · CVE-2026-23992 · CVE-2026-24122 · CVE-2026-24137 · CVE-2026-26958
openSUSE-SU-2026:21801-1: Security update for trivy
CVE-2026-24122 · CVE-2026-37236 · CVE-2026-41178 · CVE-2026-50163 · CVE-2026-56854 · CVE-2026-56855 · CVE-2026-78662 · CVE-2026-84303 · CVE-2026-84304 · CVE-2026-84445
openSUSE-SU-2026:20662-1: Security update for hauler
CVE-2026-24122
- Source published
- Feb 19, 2026, 10:27:08 PM (timezone not stated)
- Source modified
- Feb 20, 2026, 3:41:03 PM (timezone not stated)
- Saved here
- 15 Nov 2026 07:38:10 UTC
- Source terms
- ENISA EUVD · source terms and attribution apply
Original source record · Cite this exact observation · Complete original publisher JSON
Source: euvd · ENISA EUVD · source terms and attribution apply. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
EUVD CVSS 3.1 · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
nvd · CVE-2026-24122
PublishedCosign 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…
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.
Additional publisher context
NVD analysis and CPE criteria are source context, not proof that a package or your environment is affected. Complete affected data, logical configurations and SSVC are retained in the original JSON.
Source analysis status: Analyzed
Weakness classifications: CWE-295
Original publisher date fields
published: 2026-02-19T23:16:24.517
lastModified: 2026-06-17T10:22:39.833
1 source CPE criteria · context only
- cpe:2.3:a:sigstore:cosign:*:*:*:*:*:*:*:*
The original JSON retains the logical configuration operators, exclusions and version bounds.
- Source published
- 19 Feb 2026 23:16:24 UTC
- Source modified
- 17 Jun 2026 10:22:39 UTC
- Saved here
- 25 Oct 2026 05:17:36 UTC
- Source terms
- NIST NVD usage terms; underlying source attribution retained
Original source record · Cite this exact observation · Complete original publisher JSON
Source: nvd · NIST NVD usage terms; underlying source attribution retained. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS 3.1 · [email protected] · Secondary · 3.7 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
osv · GHSA-wfqv-66vq-46rm
PublishedCosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped
## 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
- Source published
- 19 Feb 2026 22:09:12 UTC
- Source modified
- 10 Sep 2026 03:50:36 UTC
- Saved here
- 24 Oct 2026 13:19:41 UTC
- Source terms
- GitHub Advisory Database · CC-BY-4.0
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · GitHub Advisory Database · CC-BY-4.0. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.
CVSS_V3 · CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N
Publisher rating · LOW
osv · GO-2026-4529
PublishedCosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped in github.com/sigstore/cosign
Cosign considered signatures valid with expired intermediate certificates when transparency log verification is skipped in github.com/sigstore/cosign
- Source published
- 23 Feb 2026 18:23:15 UTC
- Source modified
- 16 Jun 2026 16:44:28 UTC
- Saved here
- 24 Oct 2026 13:19:41 UTC
- Source terms
- OSV · upstream source license applies
Original source record · Cite this exact observation · Complete original publisher JSON
Source: osv · OSV · upstream source license applies. The publisher's wording is preserved. ChangeIntel groups the information and labels changes. The JSON record includes additional source fields.