CVE-2020-36843
MEDIUMCVE-2020-36843 is a medium-severity (CVSS 4.3) CWE-347 vulnerability in net.i2p.crypto:eddsa. O3 Security confirms whether CVE-2020-36843 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Ed25519 Signature Malleability in ed25519-java Due to Missing Scalar Range Check
Blast Radius
net.i2p.crypto:eddsa☕net.i2p:i2pReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
The implementation of EdDSA in EdDSA-Java (aka ed25519-java) through 0.3.0 exhibits signature malleability and does not satisfy the SUF-CMA (Strong Existential Unforgeability under Chosen Message Attacks) property. This allows attackers to create new valid signatures different from previous signatures for a known message.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | net.i2p.crypto:eddsa | all versions | No fix |
| ☕Maven | net.i2p:i2p | all versions | 0.9.39 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net.i2p.crypto:eddsa. 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
No patched version of net.i2p.crypto:eddsa has shipped for CVE-2020-36843 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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 CVE-2020-36843 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 CVE-2020-36843. 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-2020-36843 in your dependencies?
O3 detects CVE-2020-36843 across Maven dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.