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LOW severity

CVE-2026-54787 — sigstore-go

LOWFix: sigstore/sigstore-go@4594ab4

CVE-2026-54787 is a low-severity (CVSS 3.1) CWE-324 vulnerability in github.com/sigstore/sigstore-go. A fix is available for github.com/sigstore/sigstore-go — see the affected versions and patch details below.

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

Also known asGHSA-wqqc-jjcq-vfxmGO-2026-6162
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 2, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-54787.

EPSS Exploitation Probability

via FIRST.org ↗
0.1%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs3th percentile — riskier than 3% of all scored CVEsHighest risk
0.00%0.21%0.42%0.63%0.1%0.1%0.1%0.1%0.1%Aug 26Oct 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/sigstore/sigstore-go

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

Description

sigstore-go fails to check signature timestamps against a signing key's validity period for self-managed long-lived keys without certificates.

Impact

To verify a bundle with a self-managed long-lived key, the key needs to be wrapped in an ExpiringKey type that implies expiration semantics:

signatureVerifier, _ := signature.LoadDefaultVerifier(publicKey)
expiredKey := root.NewExpiringKey(signatureVerifier, time.Unix(0, 0), time.Unix(1, 0))

Despite the API contract, the validator does not check the bundle signing time against the validity window. Attackers that obtain expired key materials may be able to sign bundles with those materials that are accepted despite a configured expiry date. This issue only impacts the long-lived signing key workflow, and not standard deployments involving a certificate authority.

Reproduction steps

Start from a sigstore-go checkout:

git clone https://github.com/sigstore/sigstore-go.git
cd sigstore-go
git checkout 8ca80c47ef03d26ebf174db7c296700b075b2c16

Apply the patch containing the test case and associated materials:

git apply sigstore-go-public-key-validity-test.patch

Run the test:

go test ./pkg/verify -run TestPublicKeyValidityCheckedAgainstSignedTimestamp

On vulnerable code, the test fails because verification succeeds even though the trusted ExpiringKey is not valid at the signed timestamp:

--- FAIL: TestPublicKeyValidityCheckedAgainstSignedTimestamp
    signed_entity_test.go:602:
        	Error:      	An error is expected but got nil.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/sigstore/sigstore-goall versions1.2.1go get github.com/sigstore/sigstore-go@v1.2.1

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/sigstore/sigstore-go, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/sigstore/sigstore-go to 1.2.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-54787 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatLow
ProductFixed inAdvisory
Red Hat Hardened Imagesspire1-15-main-1.15.2-0.3.hum1RHSA-2026:44162
Red Hat Hardened Imagescosign-main-3.1.2-0.2.hum1RHSA-2026:44451
Red Hat Hardened Imagesspire1-14-main-1.14.7-0.3.hum1RHSA-2026:47889
Red Hat Hardened Imagestrivy-main-0.72.0-0.1.3.hum1RHSA-2026:47891

Frequently Asked Questions

sigstore-go fails to check signature timestamps against a signing key's validity period for self-managed long-lived keys without certificates. ## Impact To verify a bundle with a self-managed long-lived key, the key needs to be wrapped in an `ExpiringKey` type that implies expiration semantics: ```go signatureVerifier, _ := signature.LoadDefaultVerifier(publicKey) expiredKey := root.NewExpiringKey(signatureVerifier, time.Unix(0, 0), time.Unix(1, 0)) ``` Despite the API contract, the validator does not check the bundle signing time against the validity window. Attackers that obtain expired
O3 Security · Impact-Aware SCA

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CVE-2026-54787: sigstore-go — Fixed in 1.2.1