CVE-2023-24533 is a high-severity (CVSS 7.5) CWE-682 vulnerability in filippo.io/nistec. A fix is available for filippo.io/nistec — see the affected versions and patch details below.
Incorrect multiplication of unreduced P-256 scalars in filippo.io/nistec
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-2023-24533.
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
CVE-2023-24533 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
filippo.io/nistecReal-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
Multiplication of certain unreduced P-256 scalars produce incorrect results. There are no protocols known at this time that can be attacked due to this.
From the fix commit notes:
Unlike the rest of nistec, the P-256 assembly doesn't use complete addition formulas, meaning that p256PointAdd[Affine]Asm won't return the correct value if the two inputs are equal.
This was (undocumentedly) ignored in the scalar multiplication loops because as long as the input point is not the identity and the scalar is lower than the order of the group, the addition inputs can't be the same.
As part of the math/big rewrite, we went however from always reducing the scalar to only checking its length, under the incorrect assumption that the scalar multiplication loop didn't require reduction.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | filippo.io/nistec | all versions | 0.0.2go get filippo.io/nistec@v0.0.2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for filippo.io/nistec, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update filippo.io/nistec to 0.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2023-24533 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 CVE-2023-24533 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2023-24533. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2023-24533 in your dependencies?
O3 Security finds CVE-2023-24533 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.