CVE-2021-34584 json
CODESYS V2 web server: crafted requests could trigger a buffer over-read (DoS)
published 2021-10-26 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-21234
- cvss
- 9.1
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 1.1%
- EPSS 1.1% chance of exploitation in 30 days, percentile 65%
- public exploits
- 0
- none known
Summary
Crafted web server requests can be utilised to read partial stack or heap memory or may trigger a denial-of- service condition due to a crash in the CODESYS V2 web server prior to V1.1.9.22.
Patch / fix
- CODESYS CODESYS V2 V1.1.9.22
Exploit prediction
1.08% chance of exploitation in the next 30 days, higher than 65% of all scored CVEs (FIRST EPSS, 2026-11-08).
Exploits and checks
- tenable.com https://www.tenable.com/security/research/tra-2021-47 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| NVD | 3.1 | 9.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H |
| NVD | 2.0 | 6.4 | AV:N/AC:L/Au:N/C:P/I:N/A:P |
Affected products
- CODESYS CODESYS V2
Classification
- Weakness
-
- CWE-126 Buffer Over-read
References
-
tenable.com
/security/research/tra-2021-47
exploit, third-party-advisory
-
customers.codesys.com
/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=
vendor-advisory
Sources
- CVE List CVE-2021-34584
- NVD CVE-2021-34584
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.