Skip to content
Fencer Vulns
high 7.5

CVE-2025-53506 json

Apache Tomcat: DoS via excessive h2 streams at connection start

published 2025-07-10 15 mo ago modified 2026-09-10 1 mo ago also BIT-tomcat-2025-53506 , EUVD-2025-21032 , GHSA-25xr-qj8w-c4vf

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.1%
EPSS 2.1% chance of exploitation in 30 days, percentile 82%
public exploits
0
none known

Summary

Uncontrolled Resource Consumption vulnerability in Apache Tomcat if an HTTP/2 client did not acknowledge the initial settings frame that reduces the maximum permitted concurrent streams.

This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.8, from 10.1.0-M1 through 10.1.42, from 9.0.0.M1 through 9.0.106. The following versions were EOL at the time the CVE was created but are known to be affected: 8.5.0 through 8.5.100. Other EOL versions may also be affected.

Users are recommended to upgrade to version 11.0.9, 10.1.43 or 9.0.107, which fix the issue.

Patch / fix

  • maven org.apache.tomcat:tomcat-coyote 9.0.107, 10.1.43, 11.0.9
  • maven org.apache.tomcat.embed:tomcat-embed-core 9.0.107, 10.1.43, 11.0.9
  • bitnami tomcat 9.0.107, 10.1.43, 11.0.9
  • apache tomcat-coyote 9.0.107, 10.1.43, 11.0.9
  • apache tomcat 9.0.107, 10.1.43, 11.0.9
  • org.apache.tomcat tomcat-coyote 9.0.107, 10.1.43, 11.0.9
  • apache tomcat-embed-core 9.0.107, 10.1.43, 11.0.9
  • org.apache.tomcat.embed tomcat-embed-core 9.0.107, 10.1.43, 11.0.9
  • tomcat9 Debian 14, Debian 13, Debian 12 9.0.70-2
  • tomcat10 Debian 12 10.1.52-1~deb12u1
  • tomcat10 Debian 13 10.1.52-1~deb13u1
  • tomcat10 Debian 14 10.1.46-1
  • tomcat11 Debian 13 11.0.15-1~deb13u1
  • tomcat11 Debian 14 11.0.11-1

debian advisories DEBIAN-CVE-2025-53506

  • tomcat RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-lib RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-webapps RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-el-5.0-api RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-docs-webapp RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-jsp-3.1-api RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-admin-webapps RHEL 10.0 1:10.1.36-1.el10_0.2
  • tomcat-servlet-6.0-api RHEL 10.0 1:10.1.36-1.el10_0.2

red hat advisories RHSA-2025:14182RHSA-2025:14183RHSA-2025:14179RHSA-2025:14180RHSA-2025:14181RHSA-2025:14177

  • tomcat SLES for SAP 15 SP5, SLES for SAP 15 SP4, SLES for SAP 15 SP3 +13 more 9.0.108-150200.91.1
  • tomcat11 SLE Module for Web and Scripting 15 SP7, SLE Module for Web and Scripting 15 SP6, openSUSE Leap 15.6 11.0.9-150600.13.6.1
  • tomcat10 SLES for SAP 15 SP5, SLES 15 SP5-LTSS, SLE Module for Web and Scripting 15 SP7 +4 more 10.1.43-150200.5.48.1
  • tomcat SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 9.0.115-3.160.1
  • tomcat SLES LTSS Extended Security 12 SP5 9.0.36-3.148.1

suse advisories SUSE-SU-2026:1058-1SUSE-SU-2025:03024-1SUSE-SU-2025:02979-1SUSE-SU-2025:02978-1SUSE-SU-2025:02745-1

  • tomcat openSUSE Tumbleweed 9.0.107-1.1
  • tomcat10 openSUSE Tumbleweed 10.1.43-1.1
  • tomcat11 openSUSE Tumbleweed 11.0.9-1.1

opensuse advisories openSUSE-SU-2025:15440-1openSUSE-SU-2025:15441-1openSUSE-SU-2025:15442-1

  • tomcat AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-lib AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-webapps AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-el-3.0-api AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-docs-webapp AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-jsp-2.3-api AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-admin-webapps AlmaLinux 8 1:9.0.87-1.el8_10.6
  • tomcat-servlet-4.0-api AlmaLinux 8 1:9.0.87-1.el8_10.6

almalinux advisories ALSA-2025:14177ALSA-2025:14178ALSA-2025:14181

  • tomcat Rocky Linux 9 1:9.0.87-3.el9_6.3
  • tomcat9 Rocky Linux 10 1:9.0.87-5.el10_0.3
  • tomcat Rocky Linux 10 1:10.1.36-1.el10_0.2
  • tomcat Rocky Linux 8 1:9.0.87-1.el8_10.6

rocky linux advisories RLSA-2025:14181RLSA-2025:14178RLSA-2025:14179RLSA-2025:14177

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2025-53506 updated cvss 5.3

tomcat: Apache Tomcat denial of service

  • Red Hat Enterprise Linux 6 tomcat6, tomcat6-lib, tomcat6-log4j, tomcat6-javadoc, tomcat6-webapps, tomcat6-el-2.1-api, +4 more Red Hat Enterprise Linux 7 tomcat, tomcat-lib, tomcat-jsvc, tomcat-javadoc, tomcat-webapps, tomcat-el-2.2-api, +4 more Red Hat Enterprise Linux 8 pki-servlet-engine, pki-servlet-4.0-api Red Hat Enterprise Linux 9 pki-servlet-engine, pki-servlet-4.0-api
    affected: workaround, no fix available “Fix deferred”
  • Red Hat Enterprise Linux AppStream (v. 8) tomcat 9.0.87-1.el8_10.6, tomcat-lib 9.0.87-1.el8_10.6, tomcat-webapps 9.0.87-1.el8_10.6, tomcat-el-3.0-api 9.0.87-1.el8_10.6, tomcat-docs-webapp 9.0.87-1.el8_10.6, tomcat-jsp-2.3-api 9.0.87-1.el8_10.6, +2 more
    fixed: vendor fix RHSA-2025:14177
  • Red Hat Enterprise Linux AppStream (v. 9) tomcat 9.0.87-3.el9_6.3, tomcat-lib 9.0.87-3.el9_6.3, tomcat-webapps 9.0.87-3.el9_6.3, tomcat-el-3.0-api 9.0.87-3.el9_6.3, tomcat-docs-webapp 9.0.87-3.el9_6.3, tomcat-jsp-2.3-api 9.0.87-3.el9_6.3, +2 more
    fixed: vendor fix RHSA-2025:14181
  • Red Hat Enterprise Linux AppStream (v. 10) tomcat 10.1.36-1.el10_0.2, tomcat9 9.0.87-5.el10_0.3, tomcat-lib 10.1.36-1.el10_0.2, tomcat9-lib 9.0.87-5.el10_0.3, tomcat-webapps 10.1.36-1.el10_0.2, tomcat9-webapps 9.0.87-5.el10_0.3, +10 more
    fixed: vendor fix RHSA-2025:14179
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) tomcat 9.0.87-1.el8_8.7, tomcat-lib 9.0.87-1.el8_8.7, tomcat-webapps 9.0.87-1.el8_8.7, tomcat-el-3.0-api 9.0.87-1.el8_8.7, tomcat-docs-webapp 9.0.87-1.el8_8.7, tomcat-jsp-2.3-api 9.0.87-1.el8_8.7, +2 more
    fixed: vendor fix RHSA-2025:14182
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) tomcat 9.0.87-1.el9_2.6, tomcat-lib 9.0.87-1.el9_2.6, tomcat-webapps 9.0.87-1.el9_2.6, tomcat-el-3.0-api 9.0.87-1.el9_2.6, tomcat-docs-webapp 9.0.87-1.el9_2.6, tomcat-jsp-2.3-api 9.0.87-1.el9_2.6, +2 more
    fixed: vendor fix RHSA-2025:14183
  • Red Hat Enterprise Linux AppStream EUS (v.9.4) tomcat 9.0.87-1.el9_4.6, tomcat-lib 9.0.87-1.el9_4.6, tomcat-webapps 9.0.87-1.el9_4.6, tomcat-el-3.0-api 9.0.87-1.el9_4.6, tomcat-docs-webapp 9.0.87-1.el9_4.6, tomcat-jsp-2.3-api 9.0.87-1.el9_4.6, +2 more
    fixed: vendor fix RHSA-2025:14180
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) tomcat 9.0.87-1.el8_8.7, tomcat-lib 9.0.87-1.el8_8.7, tomcat-webapps 9.0.87-1.el8_8.7, tomcat-el-3.0-api 9.0.87-1.el8_8.7, tomcat-docs-webapp 9.0.87-1.el8_8.7, tomcat-jsp-2.3-api 9.0.87-1.el8_8.7, +2 more
    fixed: vendor fix RHSA-2025:14182
show 4 more
  • Red Hat JBoss Web Server 5.8 for RHEL 7 Server jws5-tomcat 9.0.87-12.redhat_00011.1.el7jws, jws5-tomcat-lib 9.0.87-12.redhat_00011.1.el7jws, jws5-tomcat-javadoc 9.0.87-12.redhat_00011.1.el7jws, jws5-tomcat-selinux 9.0.87-12.redhat_00011.1.el7jws, jws5-tomcat-webapps 9.0.87-12.redhat_00011.1.el7jws, jws5-tomcat-java-jdk8 9.0.87-12.redhat_00011.1.el7jws, +6 more Red Hat JBoss Web Server 5.8 for RHEL 8 jws5-tomcat 9.0.87-12.redhat_00011.1.el8jws, jws5-tomcat-lib 9.0.87-12.redhat_00011.1.el8jws, jws5-tomcat-javadoc 9.0.87-12.redhat_00011.1.el8jws, jws5-tomcat-selinux 9.0.87-12.redhat_00011.1.el8jws, jws5-tomcat-webapps 9.0.87-12.redhat_00011.1.el8jws, jws5-tomcat-el-3.0-api 9.0.87-12.redhat_00011.1.el8jws, +4 more Red Hat JBoss Web Server 5.8 for RHEL 9 jws5-tomcat 9.0.87-12.redhat_00011.1.el9jws, jws5-tomcat-lib 9.0.87-12.redhat_00011.1.el9jws, jws5-tomcat-javadoc 9.0.87-12.redhat_00011.1.el9jws, jws5-tomcat-selinux 9.0.87-12.redhat_00011.1.el9jws, jws5-tomcat-webapps 9.0.87-12.redhat_00011.1.el9jws, jws5-tomcat-el-3.0-api 9.0.87-12.redhat_00011.1.el9jws, +4 more
    fixed: vendor fix RHSA-2025:11695
  • Red Hat JBoss Web Server 5.8.5
    fixed: vendor fix RHSA-2025:11696
  • Red Hat JBoss Web Server 6.1 for RHEL 8 jws6-tomcat 10.1.36-7.redhat_00008.1.el8jws, jws6-tomcat-lib 10.1.36-7.redhat_00008.1.el8jws, jws6-tomcat-javadoc 10.1.36-7.redhat_00008.1.el8jws, jws6-tomcat-selinux 10.1.36-7.redhat_00008.1.el8jws, jws6-tomcat-webapps 10.1.36-7.redhat_00008.1.el8jws, jws6-tomcat-el-5.0-api 10.1.36-7.redhat_00008.1.el8jws, +4 more Red Hat JBoss Web Server 6.1 for RHEL 9 jws6-tomcat 10.1.36-7.redhat_00008.1.el9jws, jws6-tomcat-lib 10.1.36-7.redhat_00008.1.el9jws, jws6-tomcat-javadoc 10.1.36-7.redhat_00008.1.el9jws, jws6-tomcat-selinux 10.1.36-7.redhat_00008.1.el9jws, jws6-tomcat-webapps 10.1.36-7.redhat_00008.1.el9jws, jws6-tomcat-el-5.0-api 10.1.36-7.redhat_00008.1.el9jws, +4 more Red Hat JBoss Web Server 6.1 for RHEL 10 jws6-tomcat 10.1.36-7.redhat_00008.1.el10jws, jws6-tomcat-lib 10.1.36-7.redhat_00008.1.el10jws, jws6-tomcat-javadoc 10.1.36-7.redhat_00008.1.el10jws, jws6-tomcat-selinux 10.1.36-7.redhat_00008.1.el10jws, jws6-tomcat-webapps 10.1.36-7.redhat_00008.1.el10jws, jws6-tomcat-el-5.0-api 10.1.36-7.redhat_00008.1.el10jws, +4 more
    fixed: vendor fix RHSA-2025:11741
  • Red Hat JBoss Web Server 6.1.1
    fixed: vendor fix RHSA-2025:11742

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
15 mo ago

Exploit prediction

2.13% chance of exploitation in the next 30 days, higher than 82% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
OSV 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.apache.tomcat:tomcat-coyote
>=11.0.0-M1, <11.0.9
>=10.1.0-M1, <10.1.43
>=9.0.0.M1, <9.0.107
>=8.5.0, <=8.5.100
11.0.9
10.1.43
9.0.107
maven org.apache.tomcat.embed:tomcat-embed-core
>=8.5.0, <=8.5.100
>=9.0.0.M1, <9.0.107
>=10.1.0-M1, <10.1.43
>=11.0.0-M1, <11.0.9
9.0.107
10.1.43
11.0.9
bitnami tomcat
<9.0.107
>=10.0.0, <10.1.43
>=11.0.0, <11.0.9
9.0.107
10.1.43
11.0.9

Affected products

  • Apache Software Foundation Apache Tomcat

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.