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Fencer Intel
medium 4.3

CVE-2020-36843 json

Ed25519 Signature Malleability in ed25519-java Due to Missing Scalar Range Check

published last yr. modified last mo. also GHSA-p53j-g8pw-4w5f , EUVD-2025-6277

cvss
4.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.1%
EPSS 0.1% chance of exploitation in 30 days, percentile 3%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven net.i2p:i2p 0.9.39
  • libeddsa-java Debian 14, Debian 13 0.3.0-2.1

debian advisories DEBIAN-CVE-2020-36843

  • jpgpj SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 1.3-150200.5.3.1
  • apache-sshd SLES for SAP 15 SP6, SLES for SAP 15 SP5, SLES for SAP 15 SP4 +8 more 2.18.0-150200.5.11.1
  • ed25519-java SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +11 more 0.3.0-150200.5.9.1

suse advisories SUSE-SU-2026:2472-1SUSE-SU-2025:1029-1

  • apache-sshd openSUSE Tumbleweed 2.18.0-1.1
  • ed25519-java openSUSE Tumbleweed 0.3.0-6.1

opensuse advisories openSUSE-SU-2026:10919-1openSUSE-SU-2025:14892-1

  • ed25519-java Azure Linux 3.0 0.3.0-1

azure linux advisories AZL-73250

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2020-36843 updated cvss 4.3

d25519-java: Signature Malleability in EdDSA-Java Leading to SUF-CMA Violation

  • Red Hat All currently supported Red Hat products
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
last yr.

Exploit prediction

0.14% chance of exploitation in the next 30 days, higher than 3% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 4.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
GitHub 3.1 4.3 CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N

Affected packages

ecosystem package affected fixed in
maven net.i2p.crypto:eddsa
<=0.3.0
 no fix listed
maven net.i2p:i2p
<0.9.39
0.9.39

Affected products

  • str4d ed25519-java

Classification

Weakness
  • CWE-347 Improper Verification of Cryptographic Signature

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.