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.
CVE-2020-11993
Score 7.5 from GitHub Security Advisory published 2022-05-24. NVD baseline CVSS 7.5; sources differ by 0.0.
- 285 internet-exposed hosts are running an affected version right now
- High exploitation likelihood — EPSS 59%
A fix is available — apply it.
285 internet-exposed hosts are running an affected version of CVE-2020-11993 right now.
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- CVSS v3
- 7.5
- EG Score
- 7.5(medium)
- EPSS
- 99.0%
- KEV
- Not listed
Published
August 7, 2020
Last Modified
May 1, 2025
References (52)
- security@apachehttp://lists.opensuse.org/opensuse-security-announce/2020-08/msg00068.html
- security@apachehttp://lists.opensuse.org/opensuse-security-announce/2020-08/msg00071.html
- security@apachehttp://lists.opensuse.org/opensuse-security-announce/2020-10/msg00081.html
- security@apachehttp://packetstormsecurity.com/files/160393/Apache-2-HTTP2-Module-Concurrent-Pool-Usage.html
- security@apachehttps://httpd.apache.org/security/vulnerabilities_24.html#CVE-2020-11993
- security@apachehttps://lists.apache.org/thread.html/r06f0d87ebb6d59ed8379633f36f72f5b1f79cadfda72ede0830b42cf%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r09bb998baee74a2c316446bd1a41ae7f8d7049d09d9ff991471e8775%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r2c6083f6a2027914a0f5b54e2a1f4fa98c03f8693b58460911818255%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r3c5c3104813c1c5508b55564b66546933079250a46ce50eee90b2e36%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r5debe8f82728a00a4a68bc904dd6c35423bdfc8d601cfb4579f38bf1%40%3Cdev.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r623de9b2b2433a87f3f3a15900419fc9c00c77b26936dfea4060f672%40%3Cdev.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r76142b8c5119df2178be7c2dba88fde552eedeec37ea993dfce68d1d%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r9e9f1a7609760f0f80562eaaec2aa3c32d525c3e0fca98b475240c71%40%3Cdev.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/r9f93cf6dde308d42a9c807784e8102600d0397f5f834890708bf6920%40%3Ccvs.httpd.apache.org%3E
- security@apachehttps://lists.apache.org/thread.html/rc998b18880df98bafaade071346690c2bc1444adaa1a1ea464b93f0a%40%3Ccvs.httpd.apache.org%3E
Patch Availability(5)
| Vendor / Ecosystem | Fixed in / Patch | Released | Source |
|---|---|---|---|
| ubuntu | apache2-utils (2.4.18-2ubuntu3.17) @ xenial | 2026-05-27 | ubuntu |
| redhat | httpd:2.4-8040020210127115317.9f9e2e7e | 2021-05-18 | redhat |
| redhat | httpd24-httpd-0:2.4.34-22.el7 | 2020-12-01 | redhat |
| redhat | httpd | 2020-10-28 | redhat |
| redhat | jbcs-httpd24-openssl-chil-0:1.0.0-1.jbcs.el7 | 2020-10-28 | redhat |
Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
All Vendor Advisories
(6)
Every vendor that published an advisory referencing this CVE — pulled from our cve_vendor_advisories aggregation. Click any row for the vendor's original advisory page.
- Microsoft MSRCCVE-2020-119932020-08-18
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.
- Red HatRHBA-2020:5280MODERATE2020-08-07
RHBA-2020:5280 — Moderate
- Red HatRHSA-2020:4383MODERATE2020-08-07
RHSA-2020:4383 — Moderate
- Red HatRHSA-2020:4384MODERATE2020-08-07
RHSA-2020:4384 — Moderate
- Red HatRHSA-2021:1809MODERATE2020-08-07
RHSA-2021:1809 — Moderate
- UbuntuUSN-4458-1MEDIUM
Apache HTTP Server vulnerabilities
Data Freshness Timeline
(refreshed 11× in last 7d / 31× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:05 UTCEPSS rescore
- 2026-07-21 15:22 UTCEPSS rescore
- 2026-07-21 15:22 UTCEPSS rescore
- 2026-07-20 17:04 UTCEPSS rescore
- 2026-07-19 14:28 UTCEPSS rescore
- 2026-07-19 14:28 UTCEPSS rescore
- 2026-07-19 07:52 UTCOSV refresh
- 2026-07-19 02:26 UTCEPSS rescore
- 2026-07-19 02:26 UTCEPSS rescore
- 2026-07-16 16:59 UTCEPSS rescore
- 2026-07-16 16:59 UTCEPSS rescore
- 2026-07-15 16:55 UTCEPSS rescore
- 2026-07-13 22:27 UTCEPSS rescore
- 2026-07-13 06:10 UTCEPSS rescore
- 2026-07-13 06:10 UTCEPSS rescore
- 2026-07-12 05:44 UTCEPSS rescore
- 2026-07-11 08:24 UTCEPSS rescore
- 2026-07-08 15:11 UTCEPSS rescore
- 2026-07-05 02:27 UTCEPSS rescore
- 2026-07-01 15:03 UTCEPSS rescore
- 2026-07-01 15:03 UTCEPSS rescore
- 2026-07-01 13:46 UTCOSV refresh
- 2026-06-30 23:20 UTCEPSS rescore
- 2026-06-30 23:20 UTCEPSS rescore
- 2026-06-28 04:54 UTCEPSS rescore
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- 2026-06-28 04:54 UTCEPSS rescore
- 2026-06-27 03:06 UTCEPSS rescore
- 2026-06-25 13:47 UTCEPSS rescore
- 2026-06-25 13:47 UTCEPSS rescore
- 2026-06-23 21:31 UTCEPSS rescore
- 2026-06-23 21:31 UTCEPSS rescore
- 2026-06-21 01:57 UTCEPSS rescore
- 2026-06-21 01:57 UTCEPSS rescore
- 2026-06-17 17:50 UTCEPSS rescore
- 2026-06-17 17:50 UTCEPSS rescore
- 2026-06-16 17:50 UTCEPSS rescore
- 2026-06-16 17:50 UTCEPSS rescore
- 2026-06-15 17:46 UTCEPSS rescore
- 2026-06-14 23:15 UTCEPSS rescore
- 2026-06-14 23:15 UTCEPSS rescore
- 2026-06-13 22:58 UTCEPSS rescore
- 2026-06-13 22:58 UTCEPSS rescore
- 2026-06-13 21:13 UTCOSV refresh
- 2026-06-12 23:09 UTCEPSS rescore
- 2026-06-11 13:58 UTCEPSS rescore
- 2026-06-10 22:16 UTCEPSS rescore
- 2026-06-10 22:16 UTCEPSS rescore
- 2026-06-10 13:20 UTCEPSS rescore
- 2026-06-06 13:45 UTCEPSS rescore
- 2026-06-06 13:45 UTCEPSS rescore
- 2026-06-06 13:45 UTCEPSS rescore
- 2026-06-05 22:45 UTCEPSS rescore
- 2026-06-05 22:45 UTCEPSS rescore
- 2026-06-04 13:10 UTCEPSS rescore
- 2026-06-04 13:10 UTCEPSS rescore
- 2026-06-02 20:11 UTCEPSS rescore
- 2026-06-02 20:11 UTCEPSS rescore
- 2026-06-01 13:50 UTCEPSS rescore
- 2026-05-31 22:29 UTCEPSS rescore
- 2026-05-31 22:29 UTCEPSS rescore
- 2026-05-31 00:15 UTCEPSS rescore
- 2026-05-31 00:14 UTCEPSS rescore
- 2026-05-29 13:42 UTCEPSS rescore
- 2026-05-29 13:42 UTCEPSS rescore
- 2026-05-28 13:43 UTCEPSS rescore
- 2026-05-28 13:43 UTCEPSS rescore
- 2026-05-27 13:39 UTCEPSS rescore
- 2026-05-27 00:31 UTCEG score recompute
- 2026-05-27 00:31 UTCVendor advisory
- 2026-05-27 00:31 UTCGHSA enrichment
- 2026-05-26 13:42 UTCEPSS rescore
- 2026-05-26 13:42 UTCEPSS rescore
- 2026-05-26 07:17 UTCEPSS rescore
- 2026-05-26 07:17 UTCEPSS rescore
Frequently asked(5)
What is CVE-2020-11993?
When was CVE-2020-11993 disclosed?
Is CVE-2020-11993 actively exploited?
What is the CVSS score of CVE-2020-11993?
How do I remediate CVE-2020-11993?
Dependency Blast Radius
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