CVE-2021-42717

moderate-risk
Published 2021-12-07

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.

Do I need to act?

~
2.0% chance of exploitation in next 30 days
EPSS score — moderate exploit probability
-
Not on CISA KEV list
No confirmed active exploitation reported to CISA
?
Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
7
CVSS 7.5/10 High
NETWORK / LOW complexity

Affected Products (10)

Modsecurity
Modsecurity
Nginx Modsecurity Waf
Nginx Modsecurity Waf

Affected Vendors

Debian Oracle F5 Owasp Trustwave

References (8)

Mailing List https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html
Third Party Advisory https://www.debian.org/security/2021/dsa-5023
Patch https://www.oracle.com/security-alerts/cpuapr2022.html
Exploit https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-...
Mailing List https://lists.debian.org/debian-lts-announce/2022/05/msg00042.html
Third Party Advisory https://www.debian.org/security/2021/dsa-5023
Patch https://www.oracle.com/security-alerts/cpuapr2022.html
Exploit https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-...
47
/ 100
moderate-risk
Severity 26/34 · High
Exploitability 5/34 · Minimal
Exposure 16/34 · Moderate