CVE-2026-3706
Severity CVSS v4.0:
LOW
Type:
CWE-345
Insufficient Verification of Data Authenticity
Publication date:
08/03/2026
Last modified:
22/04/2026
Description
A vulnerability was determined in mkj Dropbear up to 2025.89. Impacted is the function unpackneg of the file src/curve25519.c of the component S Range Check. This manipulation causes improper verification of cryptographic signature. The attack can be initiated remotely. The attack is considered to have high complexity. The exploitability is considered difficult. The actual existence of this vulnerability is currently in question. Patch name: fdec3c90a15447bd538641d85e5a3e3ac981011d. To fix this issue, it is recommended to deploy a patch. The project maintainer explains: "Signature Malleability is not exploitable in SSH protocol. (...) [A] PoC doesn't exist for SSH implementation, but rather it's against the internal API."
Impact
Base Score 4.0
1.70
Severity 4.0
LOW
Base Score 3.x
3.70
Severity 3.x
LOW
Base Score 2.0
2.60
Severity 2.0
LOW
References to Advisories, Solutions, and Tools
- https://github.com/mkj/dropbear/
- https://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d
- https://github.com/mkj/dropbear/issues/406
- https://github.com/mkj/dropbear/pull/407
- https://github.com/str4d/ed25519-java/issues/82#issue-727629226
- https://vuldb.com/?ctiid.349652
- https://vuldb.com/?id.349652
- https://vuldb.com/?submit.765933
- https://github.com/mkj/dropbear/issues/406