Home/CVE/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 t
CVE

CVE-2020-13943

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 t

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.

MEDIUM · CVSS 4.3 EPSS 0.12123
Schedule remediation
  • EPSS ≥ 0.10 - elevated exploitation probability
  • EPSS percentile: top 6% of all CVEs by exploitation likelihood
Sigma rules1 YARA rules0
▤

Affected Products & Versions

1
apache tomcatall versions
▤

Affected Packages

1
Language-ecosystem packages (from OSV) tied to this CVE, with the version that fixes it - the dependency-level detail NVD doesn’t carry.
Maven org.apache.tomcat:tomcat-coyote MODERATE fixed in 10.0.0-M8
◈

Sigma Hunt Rules

1
Exact rules name this CVE ID. Product rules name an affected product in their title. Related rules cover techniques used by actors who exploited this CVE. Showing the most relevant matches; the complete related set is on the full drill-down.
productmediumTomcat WebServer Logs Deleted
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Scoring & Timeline

4.3
MEDIUM · CVSS v3.1 · security@apache.org
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD12 Oct 2020 · 02:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
⚑

Vendor Advisories

14
suse-csafSUSE-SU-2026:1058-1
suse-csafopenSUSE-SU-2024:11468-1
suse-csafopenSUSE-SU-2024:13441-1
usnUSN-5360-1
rhsaRHSA-2021:5134Critical
🔗

References & Sources

7
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00002.htmlMailing ListThird Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00021.htmlBroken Link
https://lists.apache.org/thread.html/r4a390027eb27e4550142fac6c8317cc684b157ae314d31514747f307%40%3Cannounce.tomcat.apache.org%3EVendor Advisory
https://lists.debian.org/debian-lts-announce/2020/10/msg00019.htmlThird Party Advisory
https://security.netapp.com/advisory/ntap-20201016-0007/Third Party Advisory
https://www.debian.org/security/2021/dsa-4835Third Party Advisory
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