CVE-2020-11996 — A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10
A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server co
Published
2020-06-26T17:15:10.153
Last modified
2026-10-08T22:16:56.027
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
01What is this vulnerability?
A specially crafted sequence of HTTP/2 requests sent to Apache Tomcat 10.0.0-M1 to 10.0.0-M5, 9.0.0.M1 to 9.0.35 and 8.5.0 to 8.5.55 could trigger high CPU usage for several seconds. If a sufficient number of such requests were made on concurrent HTTP/2 connections, the server could become unresponsive.
02Affected products
No structured affected-product list available — see references below for vendor advisories.
03Active exploitation status
Not currently listed on the CISA Known Exploited Vulnerabilities (KEV) catalog. EPSS is the best forward-looking signal — see the EPSS row above.
04Recommended remediation
- Patch to a fixed version listed in the vendor advisory (see references below).
- Mitigate with WAF rules, network egress filters, or feature flags where the patch is not yet available.
- Hunt historical logs for exploitation indicators — see Detection signatures below.
05Technical details
For the full vendor write-up, exploit chains, and reference implementations, see the references list in section 09.
06Detection signatures
Ask SARA in chat to draft a starting detection for this CVE in your stack of choice.
07Related CVEs
No directly-cited follow-up CVEs in the KB record for this advisory. The references list in section 09 carries the vendor cross-references.
08Timeline
- Published: 2020-06-26T17:15:10.153
- Last modified: 2026-10-08T22:16:56.027
09References
- lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00064.html
- lists.opensuse.org — http://lists.opensuse.org/opensuse-security-announce/2020-07/msg00072.html
- lists.apache.org — https://lists.apache.org/thread.html/r2529016c311ce9485e6f173446d469600fdfbb94dc…
- lists.apache.org — https://lists.apache.org/thread.html/r3ea96d8f36dd404acce83df8aeb22a9e807d6c13ca…
- lists.apache.org — https://lists.apache.org/thread.html/r5541ef6b6b68b49f76fc4c45695940116da2bcbe03…
- lists.apache.org — https://lists.apache.org/thread.html/r5a4f80a6acc6607d61dae424b643b594c6188dd4e1…
- lists.apache.org — https://lists.apache.org/thread.html/r6c29801370a36c1a5159679269777ad0c73276d301…
- lists.apache.org — https://lists.apache.org/thread.html/r74f5a8204efe574cbfcd95b2a16236fe95beb45c4d…
- lists.apache.org — https://lists.apache.org/thread.html/r8f3d416c193bc9384a8a7dd368623d441f5fcaff10…
- lists.apache.org — https://lists.apache.org/thread.html/r8f7484589454638af527182ae55ef5b628ba00c05c…
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