Apache Tomcat

Uncontrolled resource consumption in Apache Tomcat's default WebSocket chat example allows remote attackers to cause denial of service. Affected versions include 11.0.0-M20 through 11.0.24, 10.1.24 through 10.1.57, and 9.0.89 through 9.0.120; users who have removed the examples web application as recommended are not impacted. No public exploit code or active exploitation is reported.

Cluster-communication confidentiality and integrity in Apache Tomcat can be undermined because the secure-configuration requirements for the EncryptInterceptor were never clearly documented, leaving operators liable to deploy the cluster session-replication channel insecurely. The flaw affects Tomcat 7.0.100-7.0.109, 8.5.38-8.5.100, 9.0.13-9.0.119, 10.1.0-M1-10.1.56 and 11.0.0-M1-11.0.23, and is fixed in 9.0.120, 10.1.57 and 11.0.24. It carries a CVSS 9.1 (C:H/I:H) but SSVC records exploitation as none, no public exploit identified at time of analysis, and the root cause is a documentation weakness (CWE-1059) rather than a code defect.

Security constraint bypass in Apache Tomcat (8.5.0-8.5.100, 9.0.0.M1-9.0.119, 10.1.0-M1-10.1.56, 11.0.0-M1-11.0.23) lets remote attackers reach protected resources by abusing improperly handled hex URL encoding in the RewriteValve, defeating URL-pattern security constraints. Because the flaw resides in the rewrite valve, only deployments that use the RewriteValve together with security constraints are exposed, but where present an unauthenticated attacker (per CVSS PR:N) can access or manipulate resources meant to be restricted. No public exploit identified at time of analysis, and the issue is not listed in CISA KEV; EPSS data was not provided.

Authentication bypass in Apache Tomcat (7.0.0-7.0.109, 8.5.0-8.5.100, 9.0.0.M1-9.0.100, 10.1.0-M1-10.1.36, 11.0.0-M1-11.0.4) lets remote attackers authenticate without supplying the correct password when the JNDIRealm is configured to validate credentials via GSSAPI bind. The flaw (CWE-304, Missing Critical Step in Authentication) means the realm accepts a bind as successful even when the password verification step is effectively skipped. There is no public exploit identified at time of analysis, EPSS risk is low (0.21%, 12th percentile), and it is not listed in CISA KEV.

Improper Authorization (CWE-285) in Apache Tomcat's default servlet allows HTTP method-based and method-omission security constraints to be silently bypassed across all major supported Tomcat branches from 7.0.x through 11.0.x. An attacker can perform HTTP operations - such as PUT or DELETE - that the web.xml security constraint configuration was intended to restrict, potentially enabling unauthorized file upload, modification, or deletion on the default servlet's served content. No active exploitation has been confirmed (not in CISA KEV) and no CVSS score has been published at time of analysis, but the broad version range and ubiquitous deployment footprint of Tomcat make prompt patching a priority.

Replay attack vulnerability in Apache Tomcat's cluster EncryptionInterceptor allows a network-adjacent attacker to retransmit previously captured encrypted inter-node cluster messages, causing receiving nodes to accept and process them as legitimate - potentially corrupting distributed session state or triggering unintended cluster actions. All major supported branches are affected: 11.0.0-M1 through 11.0.22, 10.1.0-M1 through 10.1.55, 9.0.13 through 9.0.18, plus end-of-life branches 8.5.38-8.5.100 and 7.0.100-7.0.109. No public exploit or CISA KEV listing has been identified at time of analysis; however, the breadth of affected versions across all active and legacy branches elevates organizational exposure, particularly for environments running EOL 8.5.x or 7.x with no available patch.

Incomplete security-constraint logging in Apache Tomcat (8.5.0-8.5.100, 9.0.0.M1-9.0.118, 10.1.0-M1-10.1.55, 11.0.0-M1-11.0.22) omits special roles and empty authorization constraints when the effective web.xml is written to the log, giving administrators an inaccurate view of the deployed access-control configuration. There is no public exploit identified at time of analysis, EPSS is low (0.17%, 7th percentile), and CISA SSVC marks exploitation status as none, despite the inflated 9.1 CVSS published by Apache. The practical effect is misleading audit/diagnostic output rather than direct attacker compromise.

Improper handling of a Certificate Revocation List (CRL) error condition in Apache Tomcat's FFM-based (Foreign Function & Memory / OpenSSL) connector allows revoked client certificates to be accepted during mutual TLS authentication, defeating revocation checking. The flaw affects Tomcat 9.0.83-9.0.118, 10.1.0-M7-10.1.55, and 11.0.0-M1-11.0.22 when a CRL is configured on the FFM connector, letting an attacker holding a revoked-but-otherwise-valid client certificate reach protected resources. There is no public exploit identified at time of analysis and the issue is not on CISA KEV, though the CVSS base score is 9.1 (CWE-390).

Access-control bypass in Apache Tomcat's RewriteValve (versions 8.5.0-8.5.100, 9.0.0.M1-9.0.118, 10.1.0-M1-10.1.55, and 11.0.0-M1-11.0.22) arises because once the first condition in an OR (`[OR]`) chain matched, subsequent non-OR conditions were never evaluated. Where operators rely on chained rewrite conditions to gate or restrict requests, an attacker can satisfy only the first condition and have later guard conditions silently skipped, leading to information disclosure or unintended request routing. There is no public exploit identified at time of analysis and the issue is not listed in CISA KEV; Apache has released fixes in 11.0.23, 10.1.56, and 9.0.119.

Reflected XSS in Apache Tomcat's bundled 'number guess' example application exposes users of that demo page to script injection across all major Tomcat release lines from 7.0 through 11.0. The flaw resides in a sample JSP/servlet, not the core Tomcat runtime, meaning exploitation depends entirely on the example application being deployed and accessible - a configuration that violates standard production hardening guidance. No public exploit code or active exploitation has been identified at time of analysis; no CVSS vector was assigned by the reporter.

Authorization bypass in Apache Tomcat (versions 7.0.0-7.0.109, 8.5.0-8.5.100, 9.0.0.M1-9.0.117, 10.1.0-M1-10.1.54, and 11.0.0-M1-11.0.21) lets remote unauthenticated attackers reach protected resources when multiple security-constraint elements define an HTTP method for the same URL extension, causing method constraints to be misapplied. Per CVSS PR:N the flaw is exploitable without authentication, yielding high confidentiality and integrity impact but no availability impact (C:H/I:H/A:N). There is no public exploit identified at time of analysis; EPSS is very low (0.02%) and CISA SSVC records exploitation status as none, though the impact is rated total and the issue is automatable.

Timing side-channel in Apache Tomcat's AJP secret comparison exposes the shared AJP connector secret to remote, unauthenticated attackers capable of making precise network timing measurements. The vulnerability, tracked as CWE-208 (Observable Timing Discrepancy), affects all major Tomcat branches from 7.0.0 through current releases prior to the fixed versions, and could allow an attacker to recover the AJP shared secret through repeated probing. No public exploit code exists at time of analysis, EPSS is 0.02%, and CISA SSVC rates exploitation as none - making real-world risk low despite the network-accessible attack vector.

Information disclosure in Apache Tomcat's LockOutRealm component allows remote attackers to bypass account-lockout tracking because usernames are compared with inconsistent case sensitivity (CWE-178), enabling authentication-related information leakage across Tomcat 7.0.0-7.0.109, 8.5.0-8.5.100, 9.0.0.M1-9.0.117, 10.1.0-M1-10.1.54 and 11.0.0-M1-11.0.21. The CVSS 3.1 vector (7.5, C:H only) scopes the impact to confidentiality with no integrity or availability effect, consistent with the 'Information Disclosure' tagging. There is no public exploit identified at time of analysis, EPSS is negligible (0.02%, 5th percentile), and CISA SSVC records exploitation as none.

Authentication bypass in Apache Tomcat's DIGEST authentication implementation allows remote attackers to circumvent HTTP Digest access authentication and reach protected resources without valid credentials, affecting Tomcat 7.0.0-7.0.109, 8.5.0-8.5.100, 9.0.0.M1-9.0.117, 10.1.0-M1-10.1.54 and 11.0.0-M1-11.0.21. The NVD-published CVSS of 9.8 reflects an unauthenticated network vector with total impact, but this record is marked DEPRECATED by the CVE program and there is no public exploit identified at time of analysis, with EPSS at just 0.04% (12th percentile) and no CISA KEV listing. Impact is scoped to deployments that actually enable DIGEST authentication, which is uncommon relative to Tomcat's overall footprint.

Improper input validation in Apache Tomcat (CWE-20) affects a broad range of releases across the 8.5, 9.0, 10.0, 10.1, and 11.0 branches, with the NVD assigning a critical CVSS 9.8 and a network/no-auth vector. No public exploit has been identified at time of analysis and the EPSS probability is only 0.04% (11th percentile), and CISA SSVC records exploitation status as none. Note a signal conflict: the intelligence tags label this 'Information Disclosure' while the official CVSS claims full confidentiality, integrity, and availability impact - the terse advisory does not resolve which is correct.

Information disclosure in Apache Tomcat versions 7.0.83 through 11.0.21 exposes HTTP authentication headers to unintended hosts during WebSocket authentication handshakes, enabling credential leakage to third-party endpoints. The flaw carries a CVSS 7.3 score with partial confidentiality, integrity, and availability impact, and no public exploit identified at time of analysis. EPSS probability is very low (0.03%) but SSVC marks the issue as automatable, indicating that scripted exploitation is feasible if attacker positioning is achieved.

Denial of service in Apache Tomcat 9.x, 10.1.x, and 11.0.x allows remote unauthenticated attackers to exhaust server resources due to missing limits or throttling on a resource allocation path (CWE-770). Affected versions span 11.0.0-M1 through 11.0.21, 10.1.0-M1 through 10.1.54, and 9.0.0.M1 through 9.0.117, with older unsupported branches also implicated per the EUVD entry. No public exploit identified at time of analysis, and the EPSS score is very low (0.02%, 5th percentile), but the SSVC framework flags the issue as automatable with partial technical impact.

Missing encryption of cluster replication traffic in Apache Tomcat 11.0.20, 10.1.53, and 9.0.116 exposes sensitive session data to network-positioned attackers because the EncryptInterceptor - the clustering security control - can be bypassed due to a regression introduced by the fix for CVE-2026-29146. Listed in CISA KEV as actively exploited with a publicly available exploit, though EPSS sits at just 0.01% (1st percentile), indicating targeted rather than widespread automated exploitation. The confidentiality impact is rated High with no integrity or availability impact, consistent with CWE-311 (Missing Encryption of Sensitive Data).

Padding oracle attack in Apache Tomcat EncryptInterceptor leaks encrypted session data confidentiality across versions 7.0.100-7.0.109, 8.5.38-8.5.100, 9.0.13-9.0.115, 10.0.0-M1-10.1.52, and 11.0.0-M1-11.0.18 when default configuration is deployed. Unauthenticated remote attackers exploit oracle responses to decrypt sensitive information without authentication (CVSS:3.1 AV:N/AC:L/PR:N). CWE-209 (information exposure through error messages) enables cryptographic side-channel extraction. No public exploit identified at time of analysis; low observed exploitation activity (EPSS 0.02%).