CVE-2021-42911 json
A Format String vulnerability exists in DrayTek Vigor 2960 <= 1.5.1.3, DrayTek Vigor 3900 <= 1.5.1.3, and DrayTek Vigor 300B <= 1.5.1.3 in…
published 2022-03-29 4 y ago modified 2026-06-17 4 mo ago also EUVD-2021-29866
- cvss
- 9.8
- version 3.1, NVD
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 3.5%
- EPSS 3.5% chance of exploitation in 30 days, percentile 89%
- public exploits
- 0
- none known
Summary
A Format String vulnerability exists in DrayTek Vigor 2960 <= 1.5.1.3, DrayTek Vigor 3900 <= 1.5.1.3, and DrayTek Vigor 300B <= 1.5.1.3 in the mainfunction.cgi file via a crafted HTTP message containing malformed QUERY STRING, which could let a remote malicious user execute arbitrary code.
Exploit prediction
3.52% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- gist.github.com https://gist.github.com/Cossack9989/e9c1c2d2e69b773ca4251acdd77f2835 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| NVD | 3.1 | 9.8 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H |
| NVD | 2.0 | 7.5 | AV:N/AC:L/Au:N/C:P/I:P/A:P |
Classification
- Weakness
-
- CWE-134 Use of Externally-Controlled Format String
References
-
gist.github.com
/Cossack9989/e9c1c2d2e69b773ca4251acdd77f2835
exploit, third-party-advisory
Sources
- CVE List CVE-2021-42911
- NVD CVE-2021-42911
Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.