Vulnerability 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."
CVSS Score
LOW
Related Weaknesses (CWE)
References
- 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
FAQ
What is CVE-2026-3706?
CVE-2026-3706 is a vulnerability with a CVSS score of 3.7 (LOW). 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 verifica...
How severe is CVE-2026-3706?
CVE-2026-3706 has been rated LOW with a CVSS base score of 3.7/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-3706?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.