GHSA-cq38-jh5f-37mq
LOWsigstore-go has an unbounded loop over untrusted input can lead to endless data attack
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.
Blast Radius
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 | 0.6.1 |
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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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
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.
How O3 protects you
O3 pinpoints whether GHSA-cq38-jh5f-37mq is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
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 detects GHSA-cq38-jh5f-37mq across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.