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high 7.5

CVE-2020-11993 in the critical feed json

Apache HTTP Server versions 2.4.20 to 2.4.43 When trace/debug was enabled for the HTTP/2 module and on certain traffic edge patterns, loggi…

published 6y ago modified 2mo ago also BIT-apache-2020-11993 , EUVD-2020-4313

cvss
7.5
version 3.1, NVD
cisa kev
Not listed
not in CISA's catalog
epss
56.6%
EPSS 56.6% chance of exploitation in 30 days, percentile 99%
public exploits
0
none known

Summary

Apache HTTP Server versions 2.4.20 to 2.4.43 When trace/debug was enabled for the HTTP/2 module and on certain traffic edge patterns, logging statements were made on the wrong connection, causing concurrent use of memory pools. Configuring the LogLevel of mod_http2 above "info" will mitigate this vulnerability for unpatched servers.

Patch / fix

  • bitnami apache 2.4.44
  • apache http_server 2.4.44
  • apache2 Debian 14, Debian 13, Debian 12 2.4.46-1

debian advisories DEBIAN-CVE-2020-11993

  • apache2 Ubuntu 18.04 LTS 2.4.29-1ubuntu4.14
  • apache2 Ubuntu 20.04 LTS 2.4.41-4ubuntu3.1

ubuntu advisories UBUNTU-CVE-2020-11993

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

  • httpd RHEL 8 2.4.37-39.module+el8.4.0+9658+b87b2deb
  • mod_md RHEL 8 1:2.0.8-8.module+el8.3.0+6814+67d1e611
  • mod_ssl RHEL 8 1:2.4.37-39.module+el8.4.0+9658+b87b2deb
  • mod_ldap RHEL 8 2.4.37-39.module+el8.4.0+9658+b87b2deb
  • mod_http2 RHEL 8 1.15.7-3.module+el8.4.0+8625+d397f3da
  • httpd-tools RHEL 8 2.4.37-39.module+el8.4.0+9658+b87b2deb
  • mod_session RHEL 8 2.4.37-39.module+el8.4.0+9658+b87b2deb
  • httpd-manual RHEL 8 2.4.37-39.module+el8.4.0+9658+b87b2deb

red hat advisories RHSA-2021:1809RHSA-2020:4384RHBA-2020:5280

  • apache2 SLES for SAP 15, SLES 15-LTSS, SLE Module for Server Applications 15 SP1 +2 more 2.4.33-3.41.1
  • apache2 SLES for SAP 12 SP5, SLES for SAP 12 SP4, SLES for SAP 12 SP3 +15 more 2.4.23-29.63.1
  • apache2 SLES for SAP 15, SLES 15-LTSS, SLE Module for Server Applications 15 SP1 +2 more 2.4.33-3.33.1
  • apache2 SLE Module for Server Applications 15 SP2, SLE Module for Basesystem 15 SP2 2.4.43-3.5.1

suse advisories SUSE-SU-2020:3067-1SUSE-SU-2020:2450-1SUSE-SU-2020:2344-1SUSE-SU-2020:2311-1

  • apache2 openSUSE Leap 15.1 2.4.33-lp151.8.21.1
  • apache2 openSUSE Leap 15.1 2.4.33-lp151.8.15.1
  • apache2 openSUSE Leap 15.2 2.4.43-lp152.2.3.1

opensuse advisories openSUSE-SU-2020:1792-1openSUSE-SU-2020:1293-1openSUSE-SU-2020:1285-1

  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.5.0+2609+b30d9eec
  • mod_md AlmaLinux 8 1:2.0.8-8.module_el8.6.0+2872+fe0ff7aa
  • mod_http2 AlmaLinux 8 1.15.7-3.module_el8.5.0+2609+b30d9eec

almalinux advisories ALSA-2021:1809

  • httpd Rocky Linux 8 2.4.37-39.module+el8.4.0+571+fd70afb1
  • mod_md Rocky Linux 8 1:2.0.8-8.module+el8.5.0+695+1fa8055e
  • mod_md Rocky Linux 8 1:2.0.8-8.module+el8.4.0+553+7a69454b
  • mod_http2 Rocky Linux 8 1.15.7-3.module+el8.4.0+553+7a69454b
  • mod_http2 Rocky Linux 8 1.15.7-3.module+el8.5.0+695+1fa8055e

rocky linux advisories RLSA-2021:1809

  • apache2 Alpine 3.24, Alpine 3.23, Alpine 3.22 +13 more 2.4.46-r0

alpine advisories ALPINE-CVE-2020-11993

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

Is CVE-2020-11993 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

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-2020-11993 updated cvss 7.5

httpd: mod_http2 concurrent pool usage

  • Red Hat JBoss Enterprise Web Server 2 jbcs-httpd24, jbcs-httpd24-runtime
    affected: no fix planned “Out of support scope”
  • Red Hat Enterprise Linux AppStream (v. 8) mod_md 2.0.8-8.module+el8.3.0+6814+67d1e611, httpd 2.4.37-39.module+el8.4.0+9658+b87b2deb, mod_ssl 2.4.37-39.module+el8.4.0+9658+b87b2deb, mod_http2 1.15.7-3.module+el8.4.0+8625+d397f3da, mod_ldap 2.4.37-39.module+el8.4.0+9658+b87b2deb, httpd-tools 2.4.37-39.module+el8.4.0+9658+b87b2deb, +4 more
    fixed: vendor fix RHSA-2021:1809
  • Red Hat JBoss Core Services
    fixed: vendor fix RHSA-2020:4383
  • Red Hat JBoss Core Services on RHEL 6 Server jbcs-httpd24-apr 1.6.3-104.jbcs.el6, jbcs-httpd24-curl 7.64.1-44.jbcs.el6, jbcs-httpd24-brotli 1.0.6-38.jbcs.el6, jbcs-httpd24-httpd 2.4.37-64.jbcs.el6, jbcs-httpd24-jansson 2.11-53.jbcs.el6, jbcs-httpd24-mod_md 2.0.8-30.jbcs.el6, +26 more Red Hat JBoss Core Services on RHEL 7 Server jbcs-httpd24-apr 1.6.3-104.jbcs.el7, jbcs-httpd24-curl 7.64.1-44.jbcs.el7, jbcs-httpd24-brotli 1.0.6-38.jbcs.el7, jbcs-httpd24-httpd 2.4.37-64.jbcs.el7, jbcs-httpd24-jansson 2.11-53.jbcs.el7, jbcs-httpd24-mod_md 2.0.8-30.jbcs.el7, +27 more
    fixed: vendor fix RHSA-2020:4384
  • Red Hat Software Collections for Red Hat Enterprise Linux Server (v. 7) httpd24-httpd 2.4.34-22.el7, httpd24-mod_ssl 2.4.34-22.el7, httpd24-mod_ldap 2.4.34-22.el7, httpd24-httpd-tools 2.4.34-22.el7, httpd24-mod_session 2.4.34-22.el7, httpd24-httpd-manual 2.4.34-22.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.6) httpd24-httpd 2.4.34-22.el7, httpd24-mod_ssl 2.4.34-22.el7, httpd24-mod_ldap 2.4.34-22.el7, httpd24-httpd-tools 2.4.34-22.el7, httpd24-mod_session 2.4.34-22.el7, httpd24-httpd-manual 2.4.34-22.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Server EUS (v. 7.7) httpd24-httpd 2.4.34-22.el7, httpd24-mod_ssl 2.4.34-22.el7, httpd24-mod_ldap 2.4.34-22.el7, httpd24-httpd-tools 2.4.34-22.el7, httpd24-mod_session 2.4.34-22.el7, httpd24-httpd-manual 2.4.34-22.el7, +1 more Red Hat Software Collections for Red Hat Enterprise Linux Workstation (v. 7) httpd24-httpd 2.4.34-22.el7, httpd24-mod_ssl 2.4.34-22.el7, httpd24-mod_ldap 2.4.34-22.el7, httpd24-httpd-tools 2.4.34-22.el7, httpd24-mod_session 2.4.34-22.el7, httpd24-httpd-manual 2.4.34-22.el7, +1 more
    fixed: vendor fix RHBA-2020:5280
  • Red Hat Enterprise Linux 5 httpd 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
    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

56.60% chance of exploitation in the next 30 days, higher than 99% of all scored CVEs (FIRST EPSS, 2026-11-09).

Exploits and checks

  • packetstormsecurity.com http://packetstormsecurity.com/files/160393/Apache-2-HTTP2-Module-Concurrent-Pool-Usage.html referenced PoC, tagged "exploit" by a source, unverified

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 4.3 AV:N/AC:M/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
>=2.4.20, <2.4.44
2.4.44

Affected products

  • n/a Apache HTTP Server

Classification

Weakness
  • CWE-444 Inconsistent Interpretation of HTTP Requests
Technology feeds

References

Sources

Fencer Intel 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.