What’s Vulnerable › Vulnerabilities
CVE-2020-13943
- Severity: medium (CVSS 4.3 v3.1)
- Exploited in the wild: not listed in CISA KEV
- EPSS: 55.0% probability of exploitation in the next 30 days
- Public exploit or detection template: none known
- Published: 2020-10-12 · updated 2026-10-08
Description
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.
Affected products
- Apache Tomcat: 8.5.0, 8.5.1, 8.5.2, 8.5.3, 8.5.4, 8.5.5 (+119)
- Debian Linux: 9.0, 10.0
- Oracle Instantis Enterprisetrack: 17.1, 17.2, 17.3
- Oracle Corporation SD-WAN Edge: 9.0
References
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00002.html
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00021.html
- https://lists.apache.org/thread.html/r4a390027eb27e4550142fac6c8317cc684b157ae314d31514747f307%40%3Cannounce.tomcat.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2020/10/msg00019.html
- https://security.netapp.com/advisory/ntap-20201016-0007/
- https://www.debian.org/security/2021/dsa-4835
- https://www.oracle.com/security-alerts/cpuApr2021.html
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00002.html
- http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00021.html
- https://lists.apache.org/thread.html/r4a390027eb27e4550142fac6c8317cc684b157ae314d31514747f307%40%3Cannounce.tomcat.apache.org%3E
- https://lists.debian.org/debian-lts-announce/2020/10/msg00019.html
- https://security.netapp.com/advisory/ntap-20201016-0007/
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