CVE-2026-34486: Apache Tomcat EncryptInterceptor bypass (incomplete fix for CVE-2026-29146)

Exploited in the wild High 7.5 EPSS 98.5% Apache Tomcat

An error in the fix for CVE-2026-29146 allows the Tomcat cluster (Tribes) EncryptInterceptor, which encrypts channel messages between cluster members, to be bypassed. Only Apache Tomcat 11.0.20, 10.1.53 and 9.0.116 contain the broken fix; Apache rates it Important. It was fixed in 11.0.21, 10.1.54 and 9.0.117, and CISA added it to the Known Exploited Vulnerabilities catalog on 2026-08-04.

CVE-2026-34486CVE identifier
7.5CVSS 3.1 base score (high)
2026-08-04added to CISA's exploited list (US federal deadline 2026-08-07)
98.5%EPSS: chance of exploitation in the next 30 days (higher than 100% of CVEs)
2026-04-09published

What do these terms mean? CVE · CVSS score · exploited (KEV) · EPSS · backported fix · all terms

What to do now

Check whether you run Apache Tomcat and which version (commands below).
Install the fixed version for your system: see “Patch it” below.
Restart Tomcat after upgrading.
Because this flaw is being exploited, also check the server for signs of compromise.

Affected and fixed versions

Affected:

Apache Tomcat 11.0.20
Apache Tomcat 10.1.53
Apache Tomcat 9.0.116

Fixed in:

Apache Tomcat 11.0.21
Apache Tomcat 10.1.54
Apache Tomcat 9.0.117

Am I affected?

$CATALINA_HOME/bin/version.sh
rpm -q tomcat tomcat9
grep -rl EncryptInterceptor $CATALINA_BASE/conf/

Patch it

Use the commands for your system. Distribution packages often keep an older version number with the fix backported, so compare with the fixed package versions in the table below, not only with the upstream version.

Debian

sudo apt update
sudo apt install --only-upgrade tomcat10 tomcat11

Ubuntu

sudo apt update
sudo apt install --only-upgrade tomcat10 tomcat11

RHEL, AlmaLinux, Rocky, Oracle

sudo dnf upgrade tomcat tomcat9
sudo systemctl restart tomcat

Fedora

sudo dnf upgrade --refresh tomcat

SUSE / openSUSE

sudo zypper refresh
sudo zypper update tomcat10 tomcat11 (or tomcat)

Amazon Linux

sudo dnf upgrade --releasever=latest tomcat10 tomcat11 (or tomcat9)

Arch Linux

sudo pacman -Syu

Alpine

not packaged: upstream tarball

FreeBSD

pkg update && pkg upgrade tomcat101 tomcat110 (or tomcat9)

Docker images

docker pull tomcat:9.0.117   # or tomcat:10.1.54 / tomcat:11.0.21 or later
# recreate the container from the new image

Built from source

# upstream binary distribution: install 11.0.21, 10.1.54 or 9.0.117 (or later) from https://tomcat.apache.org/
# and point CATALINA_HOME at the new release, keeping your CATALINA_BASE configuration

General update steps for every system are on the Linux and Unix & BSD pages; after updating, see which services to restart.

Fix status in Linux distributions

Release	Package	Status	Fixed version / advisory
Debian 12	`tomcat10`	not affected
Debian 13	`tomcat10`	not affected
Debian testing	`tomcat10`	not affected
Debian 13	`tomcat11`	not affected
Debian testing	`tomcat11`	not affected
Debian 12	`tomcat9`	not affected
Debian 13	`tomcat9`	not affected
Debian testing	`tomcat9`	not affected
Red Hat Enterprise Linux 9	`tomcat-1:9.0.117-2.el9_8`	fixed	`RHSA-2026:36879`
Red Hat Enterprise Linux 9	`pki-servlet-engine`	will not fix
Red Hat Enterprise Linux 8	`tomcat-1:9.0.87-2.el8_10`	fixed	`RHSA-2026:37137`
Red Hat Enterprise Linux 6	`tomcat6`	out of support scope
Red Hat Enterprise Linux 10	`tomcat-1:10.1.49-3.el10_2`	fixed	`RHSA-2026:36788`
Red Hat Enterprise Linux 10	`tomcat9-1:9.0.117-2.el10_2`	fixed	`RHSA-2026:36790`
RHEL 10	`tomcat`	fixed	`10.1.49-3.el10_2 (RHSA-2026:36788)`
RHEL 10	`tomcat9`	fixed	`9.0.117-2.el10_2 (RHSA-2026:36790)`
RHEL 9	`tomcat`	fixed	`9.0.117-2.el9_8 (RHSA-2026:36879)`
RHEL 8	`tomcat`	fixed	`9.0.87-2.el8_10 (RHSA-2026:37137)`
Debian (all releases)	`tomcat9 / tomcat10 / tomcat11`	fixed	`not affected (the incomplete CVE-2026-29146 fix was never applied)`

From the Debian security tracker, Ubuntu CVE tracker and Red Hat Security Data API, refreshed every few hours.

CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

https://lists.apache.org/thread/9510k5p5zdvt9pkkgtyp85mvwxo2qrly ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2026-34486

Related vulnerabilities

CVE-2026-29146

Sources

Page generated automatically from official sources on 2026-11-03 18:05 UTC and reviewed by an editor. Always confirm with your vendor's advisory.