Monitor vulnerabilities like this one.
Sign up free to get alerted when software you use is affected.
6.3
Dropbear SSH Server: Signature Verification Weakness Allows Remote Attack
CVE-2026-3706
Summary
A weakness in Dropbear's cryptographic verification process can allow a remote attacker to exploit it. This can happen if the server is not updated with the latest patch. To fix this, apply the available patch to ensure the server is secure.
Original title
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 verif...
Original 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 exploit has been publicly disclosed and may be utilized. Patch name: fdec3c90a15447bd538641d85e5a3e3ac981011d. To fix this issue, it is recommended to deploy a patch.
nvd CVSS2.0
2.6
nvd CVSS3.1
3.7
nvd CVSS4.0
6.3
Vulnerability type
CWE-345
CWE-347
Improper Verification of Cryptographic Signature
- https://github.com/mkj/dropbear/
- https://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d
- https://github.com/mkj/dropbear/issues/406#issue-3978907798
- 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
Published: 8 Mar 2026 · Updated: 13 Mar 2026 · First seen: 8 Mar 2026