CVE-2020-13943If an HTTP/2 client connecting to Apache Tomcat 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37 or 8.5.0 to 8.5.57 exceeded the agreed maximum number of concurrent streams for a connection (in violation o…
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No exploitation reported and no EPSS estimate yet.
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If an HTTP/2 client connecting to Apache Tomcat 10.0.0-M1 to 10.0.0-M7, 9.0.0.M1 to 9.0.37 or 8.5.0 to 8.5.57 exceeded the agreed maximum number of concurrent streams for a connection (in violation of the HTTP/2 protocol), it was possible that a subsequent request made on that connection could contain HTTP headers - including HTTP/2 pseudo headers - from a previous request rather than the intended headers. This could lead to users seeing responses for unexpected resources.
- CVSS
- 4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- apache
- NVD analysis
- Modified
- Record last updated
- Oct 8, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
apache tomcat apache:tomcat | 8.5.0; 8.5.1; 8.5.2; 8.5.3; 8.5.4; 8.5.5; 8.5.6; 8.5.7; and 117 more ranges | NVD |
debian debian_linux debian:debian_linux | 9.0; 10.0 | NVD |
oracle instantis_enterprisetrack oracle:instantis_enterprisetrack | 17.1; 17.2; 17.3 | NVD |
oracle sd-wan_edge oracle:sd-wan_edge | 9.0 | NVD |
References
- https://lists.apache.org/thread.html/r4a390027eb27e4550142fac6c8317cc684b157ae314d31514747f307%40%3Cannounce.tomcat.apache.org%3Ex-refsource-misc
- https://lists.debian.org/debian-lts-announce/2020/10/msg00019.htmlmailing-list, x-refsource-mlist
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00002.htmlvendor-advisory, x-refsource-suse
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00021.htmlvendor-advisory, x-refsource-suse
- https://www.debian.org/security/2021/dsa-4835vendor-advisory, x-refsource-debian
- https://www.oracle.com/security-alerts/cpuApr2021.htmlx-refsource-misc
- https://security.netapp.com/advisory/ntap-20201016-0007/x-refsource-confirm
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.