mkj Dropbear S Range Check curve25519.c unpackneg signature verification
Summary
mkj Dropbear S Range Check curve25519.c unpackneg signature verification
Original description
The description as published by the source.
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."
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-3706 dropbear
- Ubuntu UBUNTU-CVE-2026-3706 dropbear
References
- advisory github.com
- advisory nvd.nist.gov
- advisory vuldb.com
- advisory vuldb.com
- patch github.com
- patch github.com
- report github.com
- report github.com
- report vuldb.com
- web github.com