How severe is CVE-2020-11993?

CVE-2020-11993 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-11993 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-11993?

CVE-2020-11993 primarily affects Apache Http Server. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-11993?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2020-11993 published?

CVE-2020-11993 was published on 2020-08-07 and last updated on 2026-06-17.

CVE-2020-11993

CVE-2020-11993 is a high-severity vulnerability in Apache Http Server with a CVSS 3.x base score of 7.5. Its EPSS exploit-prediction score of 59% places it in the 99th percentile, indicating an elevated likelihood of exploitation. The underlying weakness is classified as CWE-444.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v2: 4.3
EPSS exploit prediction: 59% (99th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-444
Affected product: Apache Http Server
Published: 2020-08-07
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-11993?: 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.
How severe is CVE-2020-11993?: CVE-2020-11993 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-11993 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 59% (99th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-11993?: CVE-2020-11993 primarily affects Apache Http Server. In total, 19 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-11993?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2020-11993 published?: CVE-2020-11993 was published on 2020-08-07 and last updated on 2026-06-17.

References

Affected products (19)

cpe:2.3:a:apache:http_server:*:*:*:*:*:*:*:*
cpe:2.3:a:netapp:clustered_data_ontap:-:*:*:*:*:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*
cpe:2.3:o:canonical:ubuntu_linux:20.04:*:*:*:lts:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.2:*:*:*:*:*:*:*
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:fedoraproject:fedora:32:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_element_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_report_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:communications_session_route_manager:*:*:*:*:*:*:*:*
cpe:2.3:a:oracle:enterprise_manager_ops_center:12.4.0.0:*:*:*:*:*:*:*
cpe:2.3:a:oracle:hyperion_infrastructure_technology:11.1.2.4:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.1:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.2:*:*:*:*:*:*:*
cpe:2.3:a:oracle:instantis_enterprisetrack:17.3:*:*:*:*:*:*:*
cpe:2.3:a:oracle:zfs_storage_appliance_kit:8.8:*:*:*:*:*:*:*

More vulnerabilities in Apache Http Server

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CVE-1999-1293 — Critical (CVSS 10.0): mod_proxy in Apache 1.2.5 and earlier allows remote attackers to cause a denial of service via malformed FTP commands,…
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All CVEs affecting Apache Http Server →

Other CWE-444 (HTTP Request/Response Smuggling) vulnerabilities

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CVE-2018-3907 — Critical (CVSS 10.0): An exploitable vulnerability exists in the REST parser of video-core's HTTP server of the Samsung SmartThings Hub…
CVE-2025-55315 — Critical (CVSS 9.9): Inconsistent interpretation of http requests ('http request/response smuggling') in ASP.NET Core allows an authorized…
CVE-2020-15049 — Critical (CVSS 9.9): An issue was discovered in http/ContentLengthInterpreter.cc in Squid before 4.12 and 5.x before 5.0.3. A Request…
CVE-2026-13763 — Critical (CVSS 9.8): Inconsistent interpretation of HTTP/2 requests in AWS Application Load Balancer with AWS WAF enabled might allow remote…

Browse all CWE-444 (HTTP Request/Response Smuggling) vulnerabilities →

Threat intelligence

Threat-intel indicators referencing this CVE:

50.255.62.89 (ipv4-addr)
147.15.15.226 (ipv4-addr)
60.199.224.2 (ipv4-addr)
46.253.45.10 (ipv4-addr)
41.225.238.233 (ipv4-addr)
31.36.163.95 (ipv4-addr)
218.51.148.194 (ipv4-addr)
211.22.166.107 (ipv4-addr)