| Name | CVE-2021-42717 |
| 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. |
| Source | CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more) |
| References | DLA-3031-1, DSA-5023-1 |
The table below lists information on source packages.
| Source Package | Release | Version | Status |
|---|---|---|---|
| modsecurity (PTS) | buster, buster (security) | 3.0.3-1+deb10u2 | vulnerable |
| bullseye | 3.0.4-2 | vulnerable | |
| bookworm | 3.0.9-1+deb12u1 | fixed | |
| trixie | 3.0.12-1 | fixed | |
| sid | 3.0.12-1.1 | fixed | |
| modsecurity-apache (PTS) | buster | 2.9.3-1+deb10u1 | fixed |
| buster (security) | 2.9.3-1+deb10u2 | fixed | |
| bullseye | 2.9.3-3+deb11u2 | fixed | |
| bullseye (security) | 2.9.3-3+deb11u1 | fixed | |
| sid, trixie, bookworm | 2.9.7-1 | fixed |
The information below is based on the following data on fixed versions.
| Package | Type | Release | Fixed Version | Urgency | Origin | Debian Bugs |
|---|---|---|---|---|---|---|
| modsecurity | source | (unstable) | 3.0.6-1 | |||
| modsecurity-apache | source | stretch | 2.9.1-2+deb9u1 | DLA-3031-1 | ||
| modsecurity-apache | source | buster | 2.9.3-1+deb10u1 | DSA-5023-1 | ||
| modsecurity-apache | source | bullseye | 2.9.3-3+deb11u1 | DSA-5023-1 | ||
| modsecurity-apache | source | (unstable) | 2.9.5-1 |
[bullseye] - modsecurity <no-dsa> (Minor issue; does not have connector packages in Debian)
[buster] - modsecurity <no-dsa> (Minor issue; does not have connector packages in Debian)
https://github.com/SpiderLabs/ModSecurity/issues/2647
https://www.trustwave.com/en-us/resources/blogs/spiderlabs-blog/modsecurity-dos-vulnerability-in-json-parsing-cve-2021-42717/
Fixed by: https://github.com/SpiderLabs/ModSecurity/commit/41918335fa4c74fba46a986771a5a6cb457070c4 (v2.9.5)
Fixed by: https://github.com/SpiderLabs/ModSecurity/commit/ac79c1c29b7e6323e26cc984ad4f76ef62c731cd (v3.0.6)