mkj Dropbear up to 2025.89 S Range Check src/curve25519.c unpackneg signature verification ⚔ [Disputed]

CVSS Meta Temp Score
CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.
Current Exploit Price (≈)
Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.
CTI Interest Score
Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
3.4$0-$5k0.00

Summaryinfo

A vulnerability, which was classified as problematic, was found in mkj Dropbear up to 2025.89. The affected element is the function unpackneg of the file src/curve25519.c of the component S Range Check. Such manipulation leads to signature verification. This vulnerability is uniquely identified as CVE-2026-3706. The attack can be launched remotely. No exploit exists. The existence of this vulnerability is still disputed at present. It is advisable to implement a patch to correct this issue. 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."

Detailsinfo

A vulnerability, which was classified as problematic, has been found in mkj Dropbear up to 2025.89. Affected by this issue is the function unpackneg of the file src/curve25519.c of the component S Range Check. The manipulation with an unknown input leads to a signature verification vulnerability. Using CWE to declare the problem leads to CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. Impacted is integrity.

The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-3706. The exploitation is known to be difficult. The attack may be launched remotely. No form of authentication is required for exploitation. There are known technical details, but no exploit is available.

The real existence of this vulnerability is still doubted at the moment. 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." The vulnerability scanner Nessus provides a plugin with the ID 301484 (Linux Distros Unpatched Vulnerability : CVE-2026-3706), which helps to determine the existence of the flaw in a target environment.

Applying the patch fdec3c90a15447bd538641d85e5a3e3ac981011d is able to eliminate this problem. The bugfix is ready for download at github.com.

The vulnerability is also documented in the databases at Tenable (301484) and EUVD (EUVD-2026-10213). github.com is providing further details. Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 3.7
VulDB Meta Temp Score: 3.4

VulDB Base Score: 3.7
VulDB Temp Score: 3.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 3.7
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
💳💳💳💳💳💳
💳💳💳💳💳💳
💳💳💳💳💳💳
VectorComplexityAuthenticationConfidentialityIntegrityAvailability
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock
UnlockUnlockUnlockUnlockUnlockUnlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Unproven

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-DayUnlockUnlockUnlockUnlock
TodayUnlockUnlockUnlockUnlock

Nessus ID: 301484
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-3706

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Patch
Status: 🔍

0-Day Time: 🔒

Patch: fdec3c90a15447bd538641d85e5a3e3ac981011d

Timelineinfo

03/07/2026 Advisory disclosed
03/07/2026 +0 days VulDB entry created
03/16/2026 +9 days VulDB entry last update

Sourcesinfo

Product: github.com

Advisory: 406
Status: Confirmed
Confirmation: 🔒
Disputed: 🔍

CVE: CVE-2026-3706 (🔒)
GCVE (CVE): GCVE-0-2026-3706
GCVE (VulDB): GCVE-100-349652
EUVD: 🔒
Misc.: 🔒

Entryinfo

Created: 03/07/2026 10:12
Updated: 03/16/2026 17:28
Changes: 03/07/2026 10:12 (62), 03/08/2026 16:21 (30), 03/09/2026 01:03 (1), 03/09/2026 05:11 (2), 03/16/2026 06:42 (16), 03/16/2026 17:28 (4)
Complete: 🔍
Submitter: pythok
Cache ID: 216:17E:103

Submitinfo

Accepted

  • Submit #765933: GitHub Dropbear 2025.89 Improper Verification of Cryptographic Signature (by pythok)

Once again VulDB remains the best source for vulnerability data.

Discussion

No comments yet. Languages: en.

Please log in to comment.

◂ PreviousOverviewNext ▸

Might our Artificial Intelligence support you?

Check our Alexa App!