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Fencer Vulns
low 3.1

CVE-2026-54787 json

sigstore-go fails to check signature timestamps against a signing key's validity period

published 2026-07-31 3 mo ago modified 2026-10-23 16 d ago also EUVD-2026-51665 , GHSA-wqqc-jjcq-vfxm , GO-2026-6162

cvss
3.1
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 2%
public exploits
0
none known

Summary

sigstore-go is a Go library for Sigstore signing and verification. Prior to 1.2.1, sigstore-go does not check a bundle signing timestamp against the validity window of an ExpiringKey wrapping a self-managed long-lived signing key without a certificate, which can allow an attacker holding expired key material to sign accepted bundles. This issue is fixed in version 1.2.1.

Patch / fix

  • go github.com/sigstore/sigstore-go 1.2.1
  • sigstore sigstore-go 1.2.1
  • sigstore-go Debian 14 1.2.1-1

debian advisories DEBIAN-CVE-2026-54787

  • cosign hummingbird 1 3.1.2-0.2.hum1
  • spire1.15 hummingbird 1 1.15.2-0.3.hum1
  • spire1.15-agent hummingbird 1 1.15.2-0.3.hum1
  • spire1.15-server hummingbird 1 1.15.2-0.3.hum1
  • spire1.15-oidc-discovery-provider hummingbird 1 1.15.2-0.3.hum1
  • trivy hummingbird 1 0.72.0-0.1.3.hum1
  • spire1.14 hummingbird 1 1.14.7-0.3.hum1
  • spire1.14-agent hummingbird 1 1.14.7-0.3.hum1

red hat advisories RHSA-2026:44451RHSA-2026:44162RHSA-2026:47891RHSA-2026:47889

  • govulncheck-vulndb SLES for SAP applications 16.0, SLES 16.0 0.0.20260827T195228-160000.1.1

suse advisories SUSE-SU-2026:23625-1

  • govulncheck-vulndb openSUSE Leap 16.0 0.0.20260827T195228-160000.1.1

opensuse advisories openSUSE-SU-2026:21761-1

  • gh Azure Linux 3.0 2.97.0-1

azure linux advisories AZL-94425

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-54787 updated cvss 3.1

github.com/sigstore/sigstore-go: sigstore-go: Signature bypass allows acceptance of bundles signed with expired keys

  • Red Hat Hardened Images cosign 3.1.2-0.2.hum1, trivy 0.72.0-0.1.3.hum1, spire1.14 1.14.7-0.3.hum1, spire1.15 1.15.2-0.3.hum1
    fixed: vendor fix RHSA-2026:44451

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3 mo ago

Exploit prediction

0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • github.com https://github.com/sigstore/sigstore-go/security/advisories/GHSA-wqqc-jjcq-vfxm referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N
GitHub 3.1 3.1 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
go github.com/sigstore/sigstore-go
<1.2.1
1.2.1

Affected products

  • sigstore sigstore-go

Classification

Weakness
  • CWE-324 Use of a Key Past its Expiration Date

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.