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Vulnerabilities

Vulnerability · CVE-2026-3706

A vulnerability was determined in mkj Dropbear up to 2025.89.

Published Mar 8, 2026 · catalog updated Oct 21, 2026 · A vulnerability was determined

Check if you run it

No confirmed exploitation is on record for CVE-2026-3706. EPSS is 0.19%. Act only if a listed version of A vulnerability was determined is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A vulnerability was determined).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Low3.7
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.19%
Remediation
Advisory link
Affected products
Ubuntu:16.04:LTS dropbear · Ubuntu:22.04:LTS dropbear · Ubuntu:24.04:LTS dropbear · Ubuntu:25.10 dropbear · Ubuntu:26.04:LTS dropbear · Ubuntu:26.10 dropbear

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."

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Ubuntu:16.04:LTS dropbear2014.65-1ubuntu2, 2015.68-1, 2015.70-1
  • Ubuntu:22.04:LTS dropbear2020.81-3, 2020.81-4, 2020.81-5
  • Ubuntu:24.04:LTS dropbear2022.83-2, 2022.83-3, 2022.83-4
  • Ubuntu:25.10 dropbear2024.86-2, 2025.88-2
  • Ubuntu:26.04:LTS dropbear2025.88-2, 2025.89-1
  • Ubuntu:26.10 dropbear2025.89-1, 2026.91-1, 2026.92-1
  • Ubuntu:Pro:18.04:LTS dropbear2017.75-2, 2017.75-3build1, 2017.75-3ubuntu0.1~esm1
  • Ubuntu:Pro:20.04:LTS dropbear2019.78-2build1, 2019.78-2ubuntu0.1~esm1

How to fix CVE-2026-3706

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-3706. EPSS is 0.19%. Act only if a listed version of A vulnerability was determined is installed.

Which versions are affected?

Compare what you have installed with 2014.65-1ubuntu2, 2015.68-1, 2015.70-1, 2020.81-3, 2020.81-4, 2020.81-5, 2022.83-2, 2022.83-3, 2022.83-4, 2024.86-2, 2025.88-2, 2025.88-2, 2025.89-1, 2025.89-1, 2026.91-1, 2026.92-1. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-345: Insufficient Verification of Data Authenticity; CWE-347: Improper Verification of Cryptographic Signature. EPSS 0.19%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Ubuntu security

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 8, 2026 · NIST NVD

    Detected

    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 vulner

  2. Jun 17, 2026 · NIST NVD

    Updated

    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 vulner

  3. Oct 21, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    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 discl

Sources

  • CVE.orgVulnerability recordCVE-2026-3706

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-3706

    30-day exploitation probability 0.19%

    first.org
  • NIST NVDVulnerability recordCVE-2026-3706

    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 attac

    nvd.nist.gov
  • OpenSSF OSV / OSV ScannerPackage advisoryUBUNTU-CVE-2026-3706
    osv.dev

References

Freshness

Last verified in this catalog Oct 23, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.