ZeroDayAlert

CVE-2026-34486: Apache Tomcat Missing Encryption of Sensitive Data Vulnerability

Apache Tomcat contains a missing encryption of sensitive data vulnerability that allows the bypass of the EncryptInterceptor. This vulnerability can be chained with CVE‑2025‑24813.

Apache Tomcat Added to KEV 2026-08-04 Federal due 2026-08-07 Known ransomware use

Required action — quoted from CISA

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.

Where this comes from. The identifier, product, dates and required action above are copied verbatim from the CISA Known Exploited Vulnerabilities catalog. The action plan below is written by an AI agent from that record and published automatically. AssurePort has not independently tested this vulnerability and makes no claim about whether any specific system is affected.

Who is affected

Apache Tomcat deployments where the EncryptInterceptor is in use for encryption of sensitive data are affected by a bypass vulnerability. The record does not specify which versions of Tomcat are vulnerable, nor does it detail the nature of the sensitive data at risk or the conditions required to exploit the bypass. Federal systems must treat this as a priority remediation based on the due date set by CISA.

How to check whether this touches you

  • Audit your inventory of web application servers to identify any running Apache Tomcat instances, noting their version and deployment context (on-premises, cloud, containerised).
  • Review your Tomcat configuration files—specifically server.xml and associated interceptor definitions—to determine whether EncryptInterceptor is explicitly configured and active.
  • Establish network reachability: identify whether each Tomcat instance is directly internet-facing, reachable from untrusted networks, or isolated to internal use only.
  • Obtain the running version of each instance (visible in logs, management interfaces, or by querying the Tomcat root application) and cross-reference against Apache's published vulnerability advisories to establish which versions are in scope.

What to do

  1. Immediate containment: If you cannot patch within the federal due date (2026-08-07), reduce network exposure by placing affected Tomcat instances behind a firewall, restricting inbound connections to known-good sources only, or disabling EncryptInterceptor if your application logic permits.
  2. Monitor for updates: Subscribe to Apache Tomcat security advisories and check the vendor's documentation for the specific patch version and instructions that address CVE-2026-34486.
  3. Plan the patch cycle: Schedule patching during a maintenance window; test the patch in a non-production environment first to confirm application compatibility.
  4. Audit your controls: Verify that any sensitive data encrypted by EncryptInterceptor has not been further protected by upstream or application-layer encryption; if not, assume it may have been readable to unauthorised parties during the exposure window.
  5. Log and alert: Enable debug logging on Tomcat interceptor activity if feasible to capture evidence of successful patch application; set alerts to fire if EncryptInterceptor is disabled or misconfigured in future.
  6. Escalate if mitigations fail: If you cannot patch and cannot reduce reachability, escalate to your risk and compliance function and consider discontinuing the product, as per CISA's required action.

If you find you were exposed

Exploitation of an encryption bypass typically occurs before disclosure becomes public, so assume that any Tomcat instance running an affected version and processing sensitive data during the vulnerability window may have been compromised. Review Tomcat access logs, application logs, and any network traffic captures retained from the period prior to patching to identify unusual data extraction patterns or unauthorised decryption requests. Your ability to detect exposure will be heavily constrained by log retention policy; prioritise retention of interceptor logs and application authentication events if your current policy permits.

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