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 the agreed maximum number of concurrent streams for a connection (in violation of
02 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
03 Exploitation and scoring
- Exploitation
- Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
- SSVC decision
- ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
- AutomatableyesAn attacker can reliably automate reconnaissance through exploitation, so this scales.
- Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
- EPSS probability
- 54.96% probability of exploitation activity in the next 30 days.
- EPSS percentile
- Equal to or higher than the score of 99.0% of scored records. A rank, not a probability.
- NVD base score
- 4.3 (CVSS v3.x), scored by the NVD independently of the CNA.
- NVD CVSS vector
- CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- NVD analysis status
- Modified. NVD last modified this record on 2026-10-08.
- Red Hat severity
- Moderate. Red Hat's rating for its own products, not a CVSS rating.
Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.
04 Metadata
- Published
- 2020-10-12 13:46Z6 YR AGO
- Last updated
- 2026-10-08 21:13Z21 DAYS AGO
- Reserved
- 2020-06-08
- Assigning CNA
- apache
- Record state
- PUBLISHED
- Severity
- Not rated by the issuing CNA
- CNA CVSS vector
- Not published by the issuing CNA
- Weaknesses
- No CWE assigned
- Data version
- 5.2
- Document digest
- 9e784743c090e404395bac902a20a3943161f9cc01058706a1c00e1c1b64d41d
05 Affected products
06 References
- lists.apache.orghttps://lists.apache.org/thread.html/r4a390027eb27e4550142fac6c8317cc684b157ae314d31514747f307%40%3Cannounce.tomcat.apache.org%3E
- lists.debian.org[debian-lts-announce] 20201014 [SECURITY] [DLA 2407-1] tomcat8 security updatehttps://lists.debian.org/debian-lts-announce/2020/10/msg00019.html
- lists.opensuse.orgopenSUSE-SU-2020:1799http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00002.html
- lists.opensuse.orgopenSUSE-SU-2020:1842http://lists.opensuse.org/opensuse-security-announce/2020-11/msg00021.html
- www.debian.orgDSA-4835https://www.debian.org/security/2021/dsa-4835
- www.oracle.comhttps://www.oracle.com/security-alerts/cpuApr2021.html
- security.netapp.comhttps://security.netapp.com/advisory/ntap-20201016-0007/
07 Fixed in
Debian 12
- tomcat9 Fixed in 9.0.38-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 13
- tomcat9 Fixed in 9.0.38-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
Debian 14
- tomcat9 Fixed in 9.0.38-1
Source: Debian Security Tracker, the Debian security team. Received through OSV.dev. Reformatted by exploit.cc.
A release or ecosystem missing from this list has no record here. It may be unaffected or not covered by the source. Source notices and licences.