GHSA-fc7x-2cmc-8j2g is a critical-severity (CVSS 9.8) Broken Cryptographic Algorithm vulnerability in sha2. A fix is available for sha2 — see the affected versions and patch details below.
Incorrect hash in sha2
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-fc7x-2cmc-8j2g 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 377,636 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
sha2Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects crates.io packages — download data is not available via public APIs for these ecosystems.
Description
The v0.9.7 release of the sha2 crate introduced a new AVX2-accelerated backend which was automatically enabled for all x86/x86_64 CPUs where AVX2 support was autodetected at runtime.
This backend was buggy and would miscompute results for long messages (i.e. messages spanning multiple SHA blocks).
The crate has since been yanked, but any users who upgraded to v0.9.7 should immediately upgrade to v0.9.8 and recompute any hashes which were previously computed by v0.9.7.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🦀crates.io | sha2 | ≥ 0.9.7&&< 0.9.8 | 0.9.8cargo update -p sha2 --precise 0.9.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for sha2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update sha2 to 0.9.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fc7x-2cmc-8j2g 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 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-fc7x-2cmc-8j2g can be triaged on real exposure rather than presence alone.
Tailored to GHSA-fc7x-2cmc-8j2g. 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-fc7x-2cmc-8j2g in your dependencies?
O3 Security finds GHSA-fc7x-2cmc-8j2g across crates.io dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.