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Fencer Vulns
high 7.5

CVE-2021-41524 in the critical feed json

null pointer dereference in h2 fuzzing

published 2021-10-05 5 y ago modified 2026-09-08 2 mo ago also BIT-apache-2021-41524 , EUVD-2021-28543

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
25.8%
EPSS 25.8% chance of exploitation in 30 days, percentile 97%
public exploits
0
none known

Summary

While fuzzing the 2.4.49 httpd, a new null pointer dereference was detected during HTTP/2 request processing, allowing an external source to DoS the server. This requires a specially crafted request. The vulnerability was recently introduced in version 2.4.49. No exploit is known to the project.

Patch / fix

  • bitnami apache 2.4.50
  • apache2 Debian 14, Debian 13, Debian 12 2.4.50-1

debian advisories DEBIAN-CVE-2021-41524

  • jbcs-httpd24-httpd jboss core services 1 2.4.51-28.el7jbcs
  • jbcs-httpd24-httpd jboss core services 1 2.4.51-28.el8jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.51-28.el7jbcs
  • jbcs-httpd24-mod_ssl jboss core services 1 1:2.4.51-28.el8jbcs
  • jbcs-httpd24-mod_ldap jboss core services 1 2.4.51-28.el7jbcs
  • jbcs-httpd24-mod_ldap jboss core services 1 2.4.51-28.el8jbcs
  • jbcs-httpd24-httpd-tools jboss core services 1 2.4.51-28.el7jbcs
  • jbcs-httpd24-httpd-tools jboss core services 1 2.4.51-28.el8jbcs

red hat advisories RHSA-2022:7143

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +11 more 2.4.50-r0

alpine advisories ALPINE-CVE-2021-41524

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • apache Arch Linux 2.4.50-1

arch linux advisories AVG-2442

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-2021-41524 updated cvss 7.5

httpd: NULL pointer dereference via crafted request during HTTP/2 request processing

  • Red Hat JBoss Enterprise Application Platform 6 httpd, mod_ssl, mod_ldap, httpd-tools, httpd-manual
    affected: no fix planned “Out of support scope”
  • Red Hat JBoss Core Services
    fixed: vendor fix RHSA-2022:7144
  • Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-httpd 2.4.51-28.el7jbcs, jbcs-httpd24-mod_ssl 2.4.51-28.el7jbcs, jbcs-httpd24-mod_ldap 2.4.51-28.el7jbcs, jbcs-httpd24-httpd-tools 2.4.51-28.el7jbcs, jbcs-httpd24-mod_session 2.4.51-28.el7jbcs, jbcs-httpd24-httpd-manual 2.4.51-28.el7jbcs, +2 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-httpd 2.4.51-28.el8jbcs, jbcs-httpd24-mod_ssl 2.4.51-28.el8jbcs, jbcs-httpd24-mod_ldap 2.4.51-28.el8jbcs, jbcs-httpd24-httpd-tools 2.4.51-28.el8jbcs, jbcs-httpd24-mod_session 2.4.51-28.el8jbcs, jbcs-httpd24-httpd-manual 2.4.51-28.el8jbcs, +2 more
    fixed: vendor fix RHSA-2022:7143
  • Red Hat Enterprise Linux 6 httpd, mod_ssl, httpd-tools, httpd-manual Red Hat Enterprise Linux 7 httpd, mod_ssl, mod_ldap, httpd-tools, mod_session, httpd-manual, +1 more Red Hat Enterprise Linux 8 httpd, mod_md, mod_ssl, mod_ldap, mod_http2, httpd-tools, +4 more Red Hat Enterprise Linux 9 httpd, mod_lua, mod_ssl, mod_ldap, httpd-core, httpd-tools, +4 more Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr 1.7.0-6.el7jbcs, jbcs-httpd24-curl 7.83.1-6.el7jbcs, jbcs-httpd24-brotli 1.0.9-2.el7jbcs, jbcs-httpd24-jansson 2.14-1.el7jbcs, jbcs-httpd24-mod_md 2.4.0-15.el7jbcs, jbcs-httpd24-libcurl 7.83.1-6.el7jbcs, +19 more Red Hat JBoss Core Services on RHEL 8 jbcs-httpd24-apr 1.7.0-6.el8jbcs, jbcs-httpd24-curl 7.83.1-6.el8jbcs, jbcs-httpd24-brotli 1.0.9-2.el8jbcs, jbcs-httpd24-jansson 2.14-1.el8jbcs, jbcs-httpd24-mod_md 2.4.0-15.el8jbcs, jbcs-httpd24-libcurl 7.83.1-6.el8jbcs, +19 more
    +1 more products
    Red Hat Software Collections httpd24-httpd, httpd24-mod_md, httpd24-mod_ssl, httpd24-mod_ldap, httpd24-httpd-tools, httpd24-mod_session, +2 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

Exploit prediction

25.80% chance of exploitation in the next 30 days, higher than 97% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
NVD 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
bitnami apache
>=2.4.49, <2.4.50
2.4.50

Affected products

  • Apache Software Foundation Apache HTTP Server

Classification

Weakness
Technology feeds

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.