GHSA-cq38-jh5f-37mq is a low-severity (CVSS 3.1) CWE-835 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 has an unbounded loop over untrusted input can lead to endless data attack
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 GHSA-cq38-jh5f-37mq.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-cq38-jh5f-37mq plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
github.com/sigstore/sigstore-goReal-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
Impact
sigstore-go is susceptible to a denial of service attack when a verifier is provided a maliciously crafted Sigstore Bundle containing large amounts of verifiable data, in the form of signed transparency log entries, RFC 3161 timestamps, and attestation subjects. The verification of these data structures is computationally expensive. This can be used to consume excessive CPU resources, leading to a denial of service attack. TUF's security model labels this type of vulnerability an "Endless data attack," and can lead to verification failing to complete and disrupting services that rely on sigstore-go for verification.
The vulnerable loops are in the verification functions in the package github.com/sigstore/sigstore-go/pkg/verify. The first is the DSSE envelope verification loop in verifyEnvelopeWithArtifact, which decodes all the digests in an attestation can be found here:
The next loop is in the VerifyArtifactTransparencyLog function, which verifies all the signed entries in a bundle:
The next loop is the VerifyTimestampAuthority function, which verifies all the RFC 3161 timestamps in a bundle:
Patches
This vulnerability is addressed with sigstore-go 0.6.1, which adds hard limits to the number of verifiable data structures that can be processed in a bundle. Verification will fail if a bundle has data that exceeds these limits. The limits are:
- 32 signed transparency log entries
- 32 RFC 3161 timestamps
- 1024 attestation subjects
- 32 digests per attestation subject
These limits are intended to be high enough to accommodate the vast majority of use cases, while preventing the verification of maliciously crafted bundles that contain large amounts of verifiable data.
Workarounds
The best way to mitigate the risk is to upgrade to sigstore-go 0.6.1 or later. Users who are vulnerable but unable to quickly upgrade may consider adding manual bundle validation to enforce limits similar to those in the referenced patch prior to calling sigstore-go's verification functions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sigstore/sigstore-go | all versions | 0.6.1go get github.com/sigstore/sigstore-go@v0.6.1 |
Detection & mitigation playbook
Open-source dependencyDetect
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.
Fix
Update github.com/sigstore/sigstore-go to 0.6.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-cq38-jh5f-37mq is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-cq38-jh5f-37mq can be triaged on real exposure rather than presence alone.
Tailored to GHSA-cq38-jh5f-37mq. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-cq38-jh5f-37mq in your dependencies?
O3 Security finds GHSA-cq38-jh5f-37mq across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.