CVE-2020-36843 Ed25519 Signature Malleability in ed25519-java Due to Missing Scalar Range Check
Attackers can generate alternative valid signatures for known messages due to signature malleability in the EdDSA-Java library, bypassing strict signature verification.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2020-36843?
CVE-2020-36843 is a medium-severity vulnerability in str4d ed25519-java, published on 13 Mar 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Official 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.
Weakness: CWE-347
Which versions are affected by CVE-2020-36843?
4 open source packages ship an affected version, including net.i2p.crypto:eddsa and net.i2p:i2p.
| Package | Affected | Fixed in |
|---|---|---|
net.i2p.crypto:eddsa Maven | All versions to 0.3.0 | None |
net.i2p.crypto:eddsa Maven | All versions to 0.3.0 | None |
net.i2p:i2p Maven | All versions | 0.9.39 |
net.i2p:i2p Maven | All versions | 0.9.39 |
Linux distribution packages (15)
ed25519-java SUSE:Enterprise Storage 7.1 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise High Performance Computing 15 SP3-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise High Performance Computing 15 SP4-ESPOS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise High Performance Computing 15 SP4-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise High Performance Computing 15 SP5-ESPOS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise High Performance Computing 15 SP5-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Module for Development Tools 15 SP6 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server 15 SP3-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server 15 SP4-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server 15 SP5-LTSS | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server for SAP Applications 15 SP3 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server for SAP Applications 15 SP4 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java SUSE:Linux Enterprise Server for SAP Applications 15 SP5 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java openSUSE:Leap 15.6 | All versions | 0.3.0-150200.5.9.1 |
ed25519-java openSUSE:Tumbleweed | All versions | 0.3.0-6.1 |
How do I fix CVE-2020-36843?
Upgrade to a fixed version.
Is CVE-2020-36843 being exploited?
There is no known exploitation of CVE-2020-36843 in the wild and no public exploit code.
Sources
Also known as AZL-73250, CLSA-2026-1770682157, DEBIAN-CVE-2020-36843, GHSA-p53j-g8pw-4w5f, MINI-65fc-pwc9-fjh6, MINI-mqwq-7r2q-x4rp and 8 more.