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."
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
High
Difficult to exploit
Attack Requirements
None
No additional conditions
Privileges Required
None
No privileges needed
User Interaction
None
No user interaction needed
Impact Assessment
Confidentiality
None
No data leak
Integrity
Low
Partial data modification
Availability
None
No disruption
CVSS Vector v4.0
Weakness Type (CWE)
References 9
https://github.com/mkj/dropbear/
cna@vuldb.com
https://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d
cna@vuldb.com
https://github.com/mkj/dropbear/issues/406#issue-3978907798
cna@vuldb.com
https://github.com/mkj/dropbear/pull/407
cna@vuldb.com
https://github.com/str4d/ed25519-java/issues/82#issue-727629226
cna@vuldb.com
https://vuldb.com/?ctiid.349652
cna@vuldb.com
https://vuldb.com/?id.349652
cna@vuldb.com
https://vuldb.com/?submit.765933
cna@vuldb.com
https://github.com/mkj/dropbear/issues/406
cna@vuldb.com