mkj Dropbear S Range Check curve25519.c unpackneg signature verification
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Attack requirements
- None
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- None · Low · None
- Fix status
- No fix listed
Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-345.
Summary
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."
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| mkj | Dropbear | 2025.0; 2025.1; 2025.2; 2025.3; 2025.4; 2025.5; 2025.6; 2025.7; 2025.8; 2025.9; 2025.10; 2025.11; 2025.12; 2025.13; 2025.14; 2025.15; 2025.16; 2025.17; 2025.18; 2025.19; 2025.20; 2025.21; 2025.22; 2025.23; 2025.24; 2025.25; 2025.26; 2025.27; 2025.28; 2025.29; 2025.30; 2025.31; 2025.32; 2025.33; 2025.34; 2025.35; 2025.36; 2025.37; 2025.38; 2025.39; 2025.40; 2025.41; 2025.42; 2025.43; 2025.44; 2025.45; 2025.46; 2025.47; 2025.48; 2025.49; 2025.50; 2025.51; 2025.52; 2025.53; 2025.54; 2025.55; 2025.56; 2025.57; 2025.58; 2025.59; 2025.60; 2025.61; 2025.62; 2025.63; 2025.64; 2025.65; 2025.66; 2025.67; 2025.68; 2025.69; 2025.70; 2025.71; 2025.72; 2025.73; 2025.74; 2025.75; 2025.76; 2025.77; 2025.78; 2025.79; 2025.80; 2025.81; 2025.82; 2025.83; 2025.84; 2025.85; 2025.86; 2025.87; 2025.88; 2025.89 | — | No fix listed | CNA |
- Dropbear Vendormkj Affected 2025.0; 2025.1; 2025.2; 2025.3; 2025.4; 2025.5; 2025.6; 2025.7; 2025.8; 2025.9; 2025.10; 2025.11; 2025.12; 2025.13; 2025.14; 2025.15; 2025.16; 2025.17; 2025.18; 2025.19; 2025.20; 2025.21; 2025.22; 2025.23; 2025.24; 2025.25; 2025.26; 2025.27; 2025.28; 2025.29; 2025.30; 2025.31; 2025.32; 2025.33; 2025.34; 2025.35; 2025.36; 2025.37; 2025.38; 2025.39; 2025.40; 2025.41; 2025.42; 2025.43; 2025.44; 2025.45; 2025.46; 2025.47; 2025.48; 2025.49; 2025.50; 2025.51; 2025.52; 2025.53; 2025.54; 2025.55; 2025.56; 2025.57; 2025.58; 2025.59; 2025.60; 2025.61; 2025.62; 2025.63; 2025.64; 2025.65; 2025.66; 2025.67; 2025.68; 2025.69; 2025.70; 2025.71; 2025.72; 2025.73; 2025.74; 2025.75; 2025.76; 2025.77; 2025.78; 2025.79; 2025.80; 2025.81; 2025.82; 2025.83; 2025.84; 2025.85; 2025.86; 2025.87; 2025.88; 2025.89 Fixed in — No fix listed CNA
Remediation
No fixed version listed by the sources yet.
Timeline
- 2026-10-02 Threatist record created from CVE-2026-3706
- 2026-10-03 Alias added: GHSA-87g2-jprq-4cmc
References
Sources
- CVE-2026-3706 · CVE Program
- CVE-2026-3706 · NVD
- FIRST EPSS
- GHSA-87g2-jprq-4cmc · GitHub Advisory Database · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences