CVE-2021-34585highCWE-252

CVE-2021-34585: high-severity vulnerability in CODESYS V2

CODESYS V2 web server: crafted requests could trigger a pointer dereference with an invalid address (DoS)

Published · Updated

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.5epss 0.9%
exploitation probability
0.9%top 41% of all CVEs
observed exploitation
nono source reports it
In short

The CODESYS V2 web server has a flaw where specially crafted requests can cause the server to crash, making it unavailable to users. This happens because the server doesn't properly check for errors when parsing these requests.

Technical detail

A remote attacker can send malformed HTTP requests to the CODESYS V2 web server (versions before V1.1.9.22) that trigger a parser error; the unchecked parser result leads to an invalid pointer dereference, causing a denial of service. No authentication or special privileges are required to exploit this vulnerability.

Summary generated and translated by AI from the official description.
In the CODESYS V2 web server prior to V1.1.9.22 crafted web server requests can trigger a parser error. Since the parser result is not checked under all conditions, a pointer dereference with an invalid address can occur. This leads to a denial of service situation.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Affected products
CODESYS · CODESYS V2
Related CVEs — CODESYS V2

In the same product, most dangerous first.

CVE-2021-34586HIGHCODESYS V2 web server: crafted requests could trigger a null pointer dereference (DoS)EPSS 14.1%CVE-2021-34583HIGHCODESYS V2 web server: crafted requests could trigger a heap-based buffer overflow (DoS)EPSS 8.4%CVE-2021-34593HIGHCODESYS V2 runtime: unauthenticated invalid requests may result in denial-of-serviceEPSS 2.7%CVE-2021-34584CRITICALCODESYS V2 web server: crafted requests could trigger a buffer over-read (DoS)EPSS 1.1%CVE-2021-34595HIGHCODESYS V2 runtime: out-of-bounds read or write access may result in denial-of-serviceEPSS 0.9%CVE-2021-34596MEDIUMCODESYS V2 runtime: Access of Uninitialized Pointer may result in denial-of-serviceEPSS 0.9%
References
https://customers.codesys.com/index.php?eID=dumpFile&t=f&f=16876&token=a3f1d937f95e7034879f4f2ea8e5a99b168256a7&download=https://www.tenable.com/security/research/tra-2021-47