CVE-2020-36843 is a medium-severity (CVSS 4.3) CWE-347 vulnerability in net.i2p.crypto:eddsa. A fix is available for net.i2p.crypto:eddsa — see the affected versions and patch details below.
Ed25519 Signature Malleability in ed25519-java Due to Missing Scalar Range Check
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-2020-36843.
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
Where this sits among everything scored
Real-World Exposure
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 | 0.9.39net.i2p:i2p: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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
A fix is available for CVE-2020-36843; check the affected-versions list above or the advisory for the patched release of net.i2p.crypto:eddsa, then make sure no transitive dependency still pins the vulnerable range.
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.
Frequently Asked Questions
Is CVE-2020-36843 in your dependencies?
Find it across Maven, including transitive dependencies.