CVE-2021-33485: codesys control Out-of-bounds Write
CVSS: 9.8v3.1CriticalModified
Published 03-08-2021Last modified 29-05-2026
Vulnerability summary
CVE-2021-33485 is a critical (CVSS 9.8) Out-of-bounds Write vulnerability in codesys control. EPSS estimates a 1.14% chance of exploitation in the next 30 days, higher than 66.2% of scored vulnerabilities.
CVSS score
9.8/10
010
Critical · v3.1 (CVE.org)EPSS score
1.14%
0%100%
Low · 0.00 pp in 30 daysKEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits0No public exploits recorded
Timeline
- 03-08-2021PublishedVulnerability first disclosed.
- 29-05-2026Last modifiedVulnerability information updated.
Description
CODESYS Control Runtime system before 3.5.17.10 has a Heap-based Buffer Overflow.
CVSS metrics
3 scores · 2 sources · 2 versionsCritical 9.8Preferred score · CVE.org (CNA)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:HSourcesAll 2 agree
- NVDNIST9.8CriticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
High 7.5Preferred score · NVD (NIST)
AV:N/AC:L/Au:N/C:P/I:P/A:PSourcesSingle source
EPSS trend
Probability
1.14%
Chance of exploitation in the next 30 days
Percentile
66%
Versus all other CVEs
30-day change
0.00 pp
From 1.14% on 19-09-2026
19-09-202619-10-2026
EPSS score1.14%
Known exploited
Compare KEV catalogsNot in any of the 3 tracked catalogs.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root cause- CWE-787Out-of-bounds WriteThe product writes data past the end, or before the beginning, of the intended buffer.
- CWE-122Heap-based Buffer OverflowA heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Affected systems
Codesys7 products
- control< 4.2.0.0 | ≤ 4.2.0.0
- control_rte< 3.5.17.10
- control_runtime_system_toolkit< 3.5.17.10
- control_win_sl< 3.5.17.10
- embedded_target_visu_toolkit< 3.5.17.10
1 vendor · 7 products