7.5

CVE-2021-42717: debian debian_linux Uncontrolled Recursion

CVSS: 7.5v3.1HighModified
AliasesMGASA-2021-0576UBUNTU-CVE-2021-42717DEBIAN-CVE-2021-42717
Published 07-12-2021Last modified 04-08-2024
Open JSON

Vulnerability summary

CVE-2021-42717 is a high (CVSS 7.5) Uncontrolled Recursion vulnerability in debian debian_linux. EPSS estimates a 3.25% chance of exploitation in the next 30 days, higher than 88.1% of scored vulnerabilities. 1 public exploit is recorded.

Overall risk
41/100
0100
Medium · default modelHow is this calculated?
CVSS score
7.5/10
010
High · v3.1 (NVD)
EPSS score
3.25%
0%100%
Low · +0.10 pp in 30 days
KEVNot listedIn no KEV catalog
RansomwareNone recordedNo known use recorded
Public exploits1reference

Advisory lineage

Upstream 0 · Downstream 3 · Related 3
OPENSUSE-SU-2023:0257-1OPENSUSE-SU-2023:0269-1USN-6370-1

Timeline

  1. 07-12-2021
    PublishedVulnerability first disclosed.
  2. 04-08-2024
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 3 sources · 2 versions

EPSS trend

Probability

3.25%

Chance of exploitation in the next 30 days

Percentile

88%

Versus all other CVEs

30-day change

+0.10 pp

From 3.15% on 18-09-2026

18-09-202618-10-2026
EPSS score
3.25%

Known exploited

Compare KEV catalogs

Not in any of the 3 tracked catalogs.

Public exploits

1 found
  • referenceUnverified

    Exploit Reference (trustwave.com)

    Maturity: unknown

Weaknesses

CWE · root cause

Affected systems

Debian3 products
  • modsecurity< 3.0.6-1
  • modsecurity-apache< 2.9.5-1 | < 2.9.3-1+deb10u1 | < 2.9.3-3+deb11u1 | < 2.9.1-2+deb9u1
  • debian_linuxEOL9.0 | 10.0 | 11.0
Oracle2 products
Ubuntu2 products
  • modsecurityAll versions (No fix recorded)
  • modsecurity-apache< 2.9.0-1ubuntu0.1~esm1 | < 2.9.2-1ubuntu0.1~esm1 | < 2.9.3-1ubuntu0.1
F51 product
Mageia1 product
  • apache-mod_security< 2.9.5-1.mga8
Owasp1 product
Trustwave1 product

7 vendors · 11 products

References

12 links
Show all 12 references