CVE-2020-11993
HighApache 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.
Published Dec 4, 2020 · Updated Sep 23, 2026 · Also known as ALPINE-CVE-2020-11993, BIT-apache-2020-11993, DEBIAN-CVE-2020-11993, SUSE-SU-2020:3067-1, UBUNTU-CVE-2020-11993
Key Facts
Patch immediately- CVE-2020-11993 is a high-severity vulnerability (CVSS 7.5 v3.1) affecting HTTP Server (Apache), Clustered Data Ontap (Netapp), Communications Element Manager (Oracle) and 22 more products.
- It is not listed in any known-exploited vulnerabilities catalog. No public exploit code is known.
- EPSS estimates a 56% probability of exploitation in the next 30 days.
- Fixed versions are available, including apache 2.4.44, HTTP Server 2.4.44, apache2 2.4.18-2ubuntu3.17.
- Brandefense priority: patch immediately, because it is very likely to be exploited soon.
CVSS v3.1
7.5
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
EPSS (30-day exploit likelihood)
56%
Higher than 99.0% of all scored CVEs
Exploited in the wild
No known
Not in a known-exploited catalog
Public exploit code
None known
Get the full CVE-2020-11993 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
Description
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.
Affected Products
305 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| HTTP ServerApache | >= 2.4.20 to 2.4.43 | 2.4.44 |
| Clustered Data OntapNetapp | See advisory | n/a |
| Communications Element ManagerOracle | See advisory | 8.2.2 |
| Communications Session Report ManagerOracle | See advisory | 8.2.2 |
| Communications Session Route ManagerOracle | See advisory | 8.2.2 |
Patched Releases
apache
2.4.44
HTTP Server
2.4.44
apache2
2.4.18-2ubuntu3.17, 2.4.23-29.63.1, 2.4.29-1ubuntu4.14, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.38-3+deb10u4, 2.4.41-4ubuntu3.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1, 2.4.46-1, 2.4.46-r0
apache2-devel
2.4.23-29.63.1, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1
apache2-doc
2.4.23-29.63.1, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1
apache2-event
2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-lp152.2.3.1
apache2-example-pages
2.4.23-29.63.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-lp152.2.3.1
apache2-prefork
2.4.23-29.63.1, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1
apache2-utils
2.4.23-29.63.1, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1
apache2-worker
2.4.23-29.63.1, 2.4.33-3.33.1, 2.4.33-3.41.1, 2.4.33-lp151.8.15.1, 2.4.33-lp151.8.21.1, 2.4.43-3.5.1, 2.4.43-lp152.2.3.1
httpd
2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb, 2.4.37-39.module+el8.4.0+571+fd70afb1, 2.4.46-1.amzn2, 2.4.46-1.ph1, 2.4.46-1.ph2, 2.4.46-1.ph3, 2.4.46-5
httpd-devel
2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb, 2.4.46-1.amzn2
httpd-filesystem
2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb, 2.4.46-1.amzn2
httpd-manual
2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb, 2.4.46-1.amzn2
httpd-tools
2.4.37-39.0.1.module+el8.4.0+20024+b87b2deb, 2.4.46-1.amzn2
httpd:2.4
8040020210127115317.9f9e2e7e
httpd24
2.4.46-1.90.amzn1
httpd24-devel
2.4.46-1.90.amzn1
httpd24-httpd
0:2.4.34-22.el7
httpd24-manual
2.4.46-1.90.amzn1
httpd24-tools
2.4.46-1.90.amzn1
jbcs-httpd24-apr
0:1.6.3-104.jbcs.el6, 0:1.6.3-104.jbcs.el7
jbcs-httpd24-apr-util
0:1.6.1-75.jbcs.el6, 0:1.6.1-75.jbcs.el7
jbcs-httpd24-brotli
0:1.0.6-38.jbcs.el6, 0:1.0.6-38.jbcs.el7
jbcs-httpd24-curl
0:7.64.1-44.jbcs.el6, 0:7.64.1-44.jbcs.el7
Timeline
Publicly disclosed
Dec 4, 2020
Last updated
Sep 23, 2026
Weakness Type
- CWE-400 Uncontrolled Resource Consumption
- CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
References
- advisoryopenSUSE-SU-2020:1285
- advisoryopenSUSE-SU-2020:1293
- advisoryopenSUSE-SU-2020:1792
- advisoryRHBA-2020:5280
- advisoryRHSA-2020:4383
FAQ
Common Questions.
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.
Affected: HTTP Server (Apache) versions >= 2.4.20 to 2.4.43; Clustered Data Ontap (Netapp); Communications Element Manager (Oracle), among others. The full list is in the CVE brief.
It is not listed in any known-exploited vulnerabilities catalog.
No, it is not currently listed in the CISA Known Exploited Vulnerabilities catalog.
No public exploit code is known.
Fixed versions are available, including apache 2.4.44, HTTP Server 2.4.44, apache2 2.4.18-2ubuntu3.17.
Brandefense priority: patch immediately, because it is very likely to be exploited soon.
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