CVE-2026-59084Network attack vector

Cluster session-data compromise via undocumented cipher constraints

Published Jul 14, 2026 · Updated Jul 14, 2026

Insufficient documentation in Apache Tomcat allows remote attackers to compromise session data through insecure EncryptInterceptor settings. The published guidance failed to state that replay protection works only with non-malleable encryption and that CBC, CFB, and OFB modes have security weaknesses. Exposure requires the optional clustering interceptor and a malleable cipher; attackers able to reach cluster traffic can replay or alter session messages, affecting confidentiality and integrity.

CVSS severity9.1
Critical
EPSS probability0.51%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Insufficient documentation in Apache Tomcat allows remote attackers to compromise session data through insecure EncryptInterceptor settings. The published guidance failed to state that replay protection works only with non-malleable encryption and that CBC, CFB, and OFB modes have security weaknesses. Exposure requires the optional clustering interceptor and a malleable cipher; attackers able to reach cluster traffic can replay or alter session messages, affecting confidentiality and integrity.

The record

CVE
CVE-2026-59084
Published
Jul 14, 2026
Updated
Jul 14, 2026
Vendor
The Apache Software Foundation
Product
Apache Tomcat
Classifications
CWE-1059, T1565.002
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 14, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 14, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=10.1.0-M1 <=10.1.56
  2. Affected versionversion=11.0.0-M1 <=11.0.23
  3. Affected versionversion=7.0.100 <=7.0.109
  4. Affected versionversion=8.5.38 <=8.5.100
  5. Affected versionversion=9.0.13 <=9.0.119

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Apache Software Foundation · Apache Tomcatversion=10.1.0-M1 <=10.1.56; version=11.0.0-M1 <=11.0.23; version=7.0.100 <=7.0.109; version=8.5.38 <=8.5.100; version=9.0.13 <=9.0.119

Published CVSS scores

9.1CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-1059Insufficient Technical Documentation
T1565.002Transmitted Data Manipulation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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