GHSA-f83f-xpx7-ffpw is a high-severity (CVSS 7.5) CWE-405 vulnerability in github.com/sigstore/fulcio. O3 Security confirms whether GHSA-f83f-xpx7-ffpw is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Fulcio allocates excessive memory during token parsing
Real-World Exposure
github.com/sigstore/fulcioReal-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
Function identity.extractIssuerURL currently splits (via a call to strings.Split) its argument (which is untrusted data) on periods.
As a result, in the face of a malicious request with an (invalid) OIDC identity token in the payload containing many period characters, a call to extractIssuerURL incurs allocations to the tune of O(n) bytes (where n stands for the length of the function's argument), with a constant factor of about 16. Relevant weakness: CWE-405: Asymmetric Resource Consumption (Amplification)
Details See identity.extractIssuerURL
Impact Excessive memory allocation
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/sigstore/fulcio | all versions | 1.8.3 |
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/fulcio. 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/fulcio to 1.8.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f83f-xpx7-ffpw 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-f83f-xpx7-ffpw 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-f83f-xpx7-ffpw. 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-f83f-xpx7-ffpw in your dependencies?
O3 detects GHSA-f83f-xpx7-ffpw across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.