CVE-2021-42717

Public Exploit

Description

ModSecurity 3.x through 3.0.5 mishandles excessively nested JSON objects. Crafted JSON objects with nesting tens-of-thousands deep could result in the web server being unable to service legitimate requests. Even a moderately large (e.g., 300KB) HTTP request can occupy one of the limited NGINX worker processes for minutes and consume almost all of the available CPU on the machine. Modsecurity 2 is similarly vulnerable: the affected versions include 2.8.0 through 2.9.4.

Category

7.5
CVSS
Severity: High
CVSS 3.1 •
CVSS 2.0 •
EPSS 2.04% Top 20%
Vendor Advisory debian.org Vendor Advisory trustwave.com
Affected: n/a n/a
Published at:
Updated at:

References

Link Tags
https://www.debian.org/security/2021/dsa-5023 vendor advisory third party advisory
https://www.oracle.com/security-alerts/cpuapr2022.html patch third party advisory
https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/ exploit mitigation vendor advisory
https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html third party advisory mailing list

Frequently Asked Questions

What is the severity of CVE-2021-42717?
CVE-2021-42717 has been scored as a high severity vulnerability.
How to fix CVE-2021-42717?
To fix CVE-2021-42717, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-42717 being actively exploited in the wild?
It is possible that CVE-2021-42717 is being exploited or will be exploited in a near future based on public information. According to its EPSS score, there is a ~2% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
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