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.

References

• https://nvd.nist.gov/vuln/detail/CVE-2026-3706
• mkj/dropbear#406 (comment)
• str4d/ed25519-java#82 (comment)
• mkj/dropbear#407
• mkj/dropbear@fdec3c9
• https://github.com/mkj/dropbear
• https://vuldb.com/?ctiid.349652
• https://vuldb.com/?id.349652
• https://vuldb.com/?submit.765933
• mkj/dropbear#406