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Fencer Vulns
high 7.5

CVE-2023-24021 json

Incorrect handling of '\0' bytes in file uploads in ModSecurity before 2.9.7 may allow for Web Application Firewall bypasses and buffer ove…

published 2023-01-20 3 y ago modified 2026-09-08 2 mo ago also BIT-modsecurity-2023-24021 , BIT-modsecurity2-2023-24021 , EUVD-2023-28085

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.9%
EPSS 0.9% chance of exploitation in 30 days, percentile 60%
public exploits
0
none known

Summary

Incorrect handling of '\0' bytes in file uploads in ModSecurity before 2.9.7 may allow for Web Application Firewall bypasses and buffer over-reads on the Web Application Firewall when executing rules that read the FILES_TMP_CONTENT collection.

Patch / fix

  • bitnami modsecurity 2.9.7
  • bitnami modsecurity2 2.9.7
  • trustwave modsecurity 2.9.7
  • modsecurity-apache Debian 14, Debian 13, Debian 12 2.9.7-1

debian advisories DEBIAN-CVE-2023-24021

  • modsecurity-apache Ubuntu 20.04 LTS 2.9.3-1ubuntu0.1
  • modsecurity-apache Ubuntu Pro 16.04 LTS 2.9.0-1ubuntu0.1~esm1
  • modsecurity-apache Ubuntu Pro 18.04 LTS 2.9.2-1ubuntu0.1~esm1
  • modsecurity-apache Ubuntu Pro 22.04 LTS 2.9.5-1ubuntu0.1~esm1

ubuntu advisories UBUNTU-CVE-2023-24021

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • jbcs-httpd24-apr jboss core services 1 1.7.0-8.el7jbcs
  • jbcs-httpd24-apr jboss core services 1 1.7.0-8.el8jbcs
  • jbcs-httpd24-curl jboss core services 1 8.2.1-1.el7jbcs
  • jbcs-httpd24-curl jboss core services 1 8.2.1-1.el8jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.57-5.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.57-5.el8jbcs
  • jbcs-httpd24-libcurl jboss core services 1 8.2.1-1.el7jbcs
  • jbcs-httpd24-libcurl jboss core services 1 8.2.1-1.el8jbcs

red hat advisories RHSA-2023:4629

  • apache2-mod_security2 SLES for SAP 15 SP3, SLES for SAP 15 SP2, SLES for SAP 15 SP1 +13 more 2.9.2-150000.3.9.1
  • apache2-mod_security2 SLE Module for Server Applications 15 SP4, openSUSE Leap 15.4 2.9.4-150400.3.6.1

suse advisories SUSE-SU-2023:0447-1SUSE-SU-2023:0431-1

  • mod_security Azure Linux 3.0 2.9.7-8

azure linux advisories AZL-44475

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2023-24021 updated cvss 7.5

modsecurity: lacking the complete content in FILES_TMP_CONTENT leads to web application firewall bypass

  • Red Hat Enterprise Linux 7 mod_security, mod_security-mlogc
    affected: workaround, no fix planned “Out of support scope”
  • Red Hat Enterprise Linux 8 mod_security, mod_security-mlogc Red Hat Enterprise Linux 9 mod_security, mod_security-mlogc Red Hat Software Collections httpd24-mlogc, httpd24-mod_security
    affected: workaround, no fix planned “Will not fix”
  • Red Hat JBoss Core Services 2.4.57
    fixed: vendor fix RHSA-2023:4628
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-mod_security 2.9.3-29.el7jbcs Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-mod_security 2.9.3-29.el8jbcs
    fixed: vendor fix RHSA-2023:4629
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr 1.7.0-8.el7jbcs, jbcs-httpd24-curl 8.2.1-1.el7jbcs, jbcs-httpd24-httpd 2.4.57-5.el7jbcs, jbcs-httpd24-libcurl 8.2.1-1.el7jbcs, jbcs-httpd24-mod_md 2.4.0-25.el7jbcs, jbcs-httpd24-mod_ssl 2.4.57-5.el7jbcs, +18 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-apr 1.7.0-8.el8jbcs, jbcs-httpd24-curl 8.2.1-1.el8jbcs, jbcs-httpd24-httpd 2.4.57-5.el8jbcs, jbcs-httpd24-libcurl 8.2.1-1.el8jbcs, jbcs-httpd24-mod_md 2.4.0-25.el8jbcs, jbcs-httpd24-mod_ssl 2.4.57-5.el8jbcs, +18 more
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
19 mo ago

Exploit prediction

0.93% chance of exploitation in the next 30 days, higher than 60% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

Affected packages

ecosystem package affected fixed in
bitnami modsecurity
<2.9.7
2.9.7
bitnami modsecurity2
<2.9.7
2.9.7

Classification

Weakness
  • CWE-170 Improper Null Termination

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.