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CVE-2020-13934

60
FAUCET Score

CVE-2020-13934 describes a denial-of-service vulnerability in Apache Tomcat versions 10.0.0-M1 to 10.0.0-M6, 9.0.0.M5 to 9.0.36, and 8.5.1 to 8.5.56, affecting various distributions including Canonical, Debian, and Oracle. The flaw allows an unauthenticated attacker to trigger an OutOfMemoryException by repeatedly making h2c direct connections that fail to release the HTTP/1.1 processor after upgrading to HTTP/2. With a CVSS score of 7.5 (High), this vulnerability is easily exploitable over the network with low attack complexity, leading to a complete loss of availability. There is currently no evidence of active exploitation, public exploit code (Metasploit, Nuclei, ExploitDB), or significant community discussion or media coverage.

Impacted Technologies

VendorProductVersion(s)CPE
>= 8.5.1, <= 8.5.56CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
>= 9.0.1, <= 9.0.36CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:*:*:*:*:*:*:*:*
9.0.0CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:9.0.0:milestone10:*:*:*:*:*:*
9.0.0CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:9.0.0:milestone11:*:*:*:*:*:*
9.0.0CPE matchmatch criteria
cpe:2.3:a:apache:tomcat:9.0.0:milestone12:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

7.5HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
NONE
Integrity Impact
NONE
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
3.6
CvssVersion
3.1

Exploit Intelligence

EPSS Score
64.12%
Probability of exploitation in next 30 days
EPSS Percentile
99.1%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.6412 is in the 99th percentile among its peer group of 51,506 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.0 Reddit, 0.1 Bluesky, 0.1 Mastodon, and 0.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.1 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (14)

mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 8.5.56
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 10.0.0-M6
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcatFixed in: 9.0.36
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcat-coyoteFixed in: 8.5.56
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcat-coyoteFixed in: 10.0.0-M6
mavenpatch availablevia ghsa
Product: org.apache.tomcat:tomcat-coyoteFixed in: 9.0.36
oraclepatch availablevia nvd_reference
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Fuse 7.9Fixed in: tomcat
View patch
redhatpatch availablevia redhat_api
Product: Red Hat JBoss Web Server 5.3 on RHEL 6Fixed in: jws5-tomcat-0:9.0.30-5.redhat_6.1.el6jws
View patch
redhatpatch availablevia redhat_api
Product: Red Hat JBoss Web Server 5.3 on RHEL 7Fixed in: jws5-tomcat-0:9.0.30-5.redhat_6.1.el7jws
View patch
redhatpatch availablevia redhat_api
Product: Red Hat JBoss Web Server 5.3 on RHEL 8Fixed in: jws5-tomcat-0:9.0.30-5.redhat_6.1.el8jws
View patch
redhatpatch availablevia redhat_api
Product: Red Hat JBoss Web Server (JWS) 5.3Fixed in: tomcat
View patch
redhatpatch availablevia redhat_api
Product: Red Hat Runtimes Spring Boot 2.2.6Fixed in: tomcat
View patch
redhatvendor investigatingvia redhat_api
Product: Red Hat Enterprise Linux 8Fixed in: pki-deps:10.6/pki-servlet-engine

Vendor Advisories (2)

mavenGHSA-vf77-8h7g-gghphigh

Improper Restriction of Operations within the Bounds of a Memory Buffer in Apache Tomcat

Feb 8, 2022
redhatCVE-2020-13934Important

tomcat: OutOfMemoryException caused by HTTP/2 connection leak could lead to DoS

Jul 15, 2020

References

lists.opensuse.org / opensuse-security-announce/2020-07/msg00084.html
Mailing ListThird Party Advisory
lists.opensuse.org / opensuse-security-announce/2020-07/msg00088.html
Mailing ListThird Party Advisory
lists.apache.org / thread.html/r61f411cf82488d6ec213063fc15feeeb88e31b0ca9c29652ee4f962e%40%3Cannounce.tomcat.apache.org%3E
Mailing ListRelease NotesVendor Advisory
lists.apache.org / thread.html/ra072b1f786e7d139e86f1d1145572e0ff71cef38a96d9c6f5362aac8%40%3Cdev.tomcat.apache.org%3E
lists.debian.org / debian-lts-announce/2020/07/msg00017.html
Mailing ListThird Party Advisory
security.netapp.com / advisory/ntap-20200724-0003
Third Party Advisory
usn.ubuntu.com / 4596-1
Third Party Advisory
debian.org / security/2020/dsa-4727
Third Party Advisory
oracle.com / security-alerts/cpuApr2021.html
PatchThird Party Advisory
oracle.com / security-alerts/cpujan2021.html
PatchThird Party Advisory
oracle.com / security-alerts/cpujan2022.html
PatchThird Party Advisory
oracle.com / /security-alerts/cpujul2021.html
PatchThird Party Advisory
oracle.com / security-alerts/cpuoct2020.html
PatchThird Party Advisory