CVE-2026-3706
Publication date 9 March 2026
Last updated 9 March 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| dropbear | 25.10 questing |
Needs evaluation
|
| 24.04 LTS noble |
Needs evaluation
|
|
| 22.04 LTS jammy |
Needs evaluation
|
|
| 20.04 LTS focal |
Needs evaluation
|
|
| 18.04 LTS bionic |
Needs evaluation
|
|
| 16.04 LTS xenial |
Needs evaluation
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
3.7 · Low
|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | None |
| Scope | Unchanged |
| Confidentiality | None |
| Integrity impact | Low |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N |
References
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-3706
- https://github.com/mkj/dropbear/issues/406
- https://github.com/mkj/dropbear/pull/407
- https://github.com/mkj/dropbear/
- https://github.com/mkj/dropbear/commit/fdec3c90a15447bd538641d85e5a3e3ac981011d
- https://github.com/mkj/dropbear/issues/406#issue-3978907798
- 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