Critical Cryptography

CVE-2025-66614 — Apache Tomcat: Client certificate verification bypass due to virtual host mapping

Improper Input Validation vulnerability. This issue affects Apache Tomcat: from 11.0.0-M1 through 11.0.14, from 10.1.0-M1 through 10.1.49, from 9.0.0-M1 through 9.0.112. 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. Older EOL versions are not affected. Tomcat did not validate that the host name provided via the SNI extension was the same as the host name provided in the HTTP host header field. If Tomcat was configured with more than one virtual host and the TLS configuration for one of those hosts did not require client certificate authentication but another one did, it was possible for a client to bypass the client certificate authentication by sending different host names in the SNI extension and the HTTP host header field. The vulnerability only applies if client certificate authentication is only enforced at the Connector. It does not apply if client certificate authentication is enforced at the web application. Users are recommended to upgrade to version 11.0.15 or later, 10.1.50 or later or 9.0.113 or later, which fix the issue.

Published Feb 17, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: apache

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+2
Technical severity (critical)+10

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.24%

ahead of 14% of scored CVEs · Oct 14, 2026

Affects

Apache Software Foundation

Tomcat

CVSS base

9.1

Critical · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Apache Software Foundation Tomcat).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (cryptography), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Apache Software Foundation	Tomcat	version 11.0.0-milestone1version 11.0.0-milestone18version 11.0.0-milestone17version 11.0.0-milestone16version 11.0.0-milestone15version 11.0.0-milestone14version 11.0.0-milestone13version 11.0.0-milestone12 and 68 more version 11.0.0-milestone11version 11.0.0-milestone10version 11.0.0-milestone19version 10.1.0-milestone9version 10.1.0-milestone8version 10.1.0-milestone7version 10.1.0-milestone6version 10.1.0-milestone5version 10.1.0-milestone4version 10.1.0-milestone3version 10.1.0-milestone20version 10.1.0-milestone2version 11.0.0-milestone4version 11.0.0-milestone9version 11.0.0-milestone8version 11.0.0-milestone7version 11.0.0-milestone6version 11.0.0-milestone5version 10.1.0-milestone19version 11.0.0-milestone3version 11.0.0-milestone26version 11.0.0-milestone25version 11.0.0-milestone24version 11.0.0-milestone23version 11.0.0-milestone22version 11.0.0-milestone21version 11.0.0-milestone20version 11.0.0-milestone2version 9.0.0-milestone16version 9.0.0-milestone24version 9.0.0-milestone23version 9.0.0-milestone22version 9.0.0-milestone21version 9.0.0-milestone20version 9.0.0-milestone2version 9.0.0-milestone19version 9.0.0-milestone18version 9.0.0-milestone17version 9.0.0-milestone25version 9.0.0-milestone15version 9.0.0-milestone14version 9.0.0-milestone13version 9.0.0-milestone12version 9.0.0-milestone11version 9.0.0-milestone10version 9.0.0-milestone1≥ 11.0.1 and < 11.0.15≥ 10.1.1 and < 10.1.50version 10.1.0-milestone1version 10.1.0-milestone18version 10.1.0-milestone17version 10.1.0-milestone16version 10.1.0-milestone15version 10.1.0-milestone14version 10.1.0-milestone13version 10.1.0-milestone12version 10.1.0-milestone11version 10.1.0-milestone10≥ 9.0.1 and < 9.0.113version 9.0.0-milestone9version 9.0.0-milestone8version 9.0.0-milestone7version 9.0.0-milestone6version 9.0.0-milestone5version 9.0.0-milestone4version 9.0.0-milestone3version 9.0.0-milestone27version 9.0.0-milestone26	Vulnerable	NIST National Vulnerability Database
Apache Software Foundation	Tomcat	≥ 8.5.0 and ≤ 8.5.100≥ 9.0.0-M1 and ≤ 9.0.112≥ 10.1.0-M1 and ≤ 10.1.49≥ 11.0.0-M1 and ≤ 11.0.14	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
9.1	CVSS 3.1	Critical	3.9	5.2	nvd@nist.gov via NIST National Vulnerability Database
7.6	CVSS 3.1	High	2.8	4.7	134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
7.6	CVSS 3.1	High	—	—	CISA-ADP via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N (score shown at the top: nvd@nist.gov)

Scoring entities (NIST, CNA, ADP) score independently; each score is shown with its origin. For prioritization we use 9.1 (NVD (NIST)) as a conservative provisional reference — not a definitive official score.

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-295 · Improper Certificate Validation

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.24%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Check TLS negotiations and unexpected certificates in the component’s traffic.

web/proxy/WAF logsnetwork IDS/IPS

Timeline

What happened to this CVE, newest first.

2026
Affected products added · apache software foundation/apache tomcat
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 9.1
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Modified
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Feb 17, 2026 · apache

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

lists.apache.org/thread/vw6lxtlh2qbqwpb61wd3sv1flm2nttw7
Mailing List, Vendor Advisory, vendor-advisory, NIST National Vulnerability Database

Elsewhere on this site

Apache Software Foundation
every CVE for this vendor

Cryptography
same class

CWE-295
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-73180 Insufficient Session Expiration vulnerability in Apache Tomcat meant that if the session… Aug 25, 2026
High CVE-2026-65183 TOCTOU Race Condition in Apache Software Foundation Tomcat Aug 25, 2026
Critical CVE-2026-65637 Improper Input Validation in Apache Software Foundation Tomcat Aug 25, 2026
Critical CVE-2026-65905 Authentication Bypass by Capture-replay in Apache Software Foundation Tomcat Aug 25, 2026
High CVE-2026-65927 Off-by-one Error vulnerability in Apache Tomcat impacting the [N] flag on the rewrite… Aug 25, 2026
Critical CVE-2026-68525 Incorrect Authorization in Apache Software Foundation Tomcat Aug 25, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2025-66614 is "Apache Tomcat: Client certificate verification bypass due to virtual host mapping", rated Critical. It affects Tomcat (Apache Software Foundation); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 9.1 describes technical severity. EPSS 0.24% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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