CVE-2026-86246: Apache Tomcat Native: Insecure OpenSSL options enabled
Apache Tomcat Native enables insecure OpenSSL options by default, tracked as CVE-2026-86246.
Mark Thomas disclosed CVE-2026-86246, rated moderate, in Apache Tomcat Native. Versions 2.0.0 through 2.0.15 and 1.3.0 through 1.3.8 initialize TLS with insecure OpenSSL defaults, including ALLOW_CLIENT_RENEGOTIATION, NO_EXTENDED_MASTER_SECRET, IGNORE_UNEXPECTED_EOF, and ALLOW_NO_DHE_KEX. The oss-security post does not describe active exploitation.
- Moderate-severity insecure OpenSSL defaults in Tomcat Native
- Affects 1.3.0–1.3.8 and 2.0.0–2.0.15
- Options include client renegotiation and no extended master secret
- No in-the-wild exploitation is reported
Vulnerabilities mentionedAll →
- CVE-2026-862469.1—Insecure TLS defaults in Apache Tomcat Native enable man-in-the-middle decryptionpublished · Apache Tomcat Native
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-86246 | Insecure TLS defaults in Apache Tomcat Native enable man-in-the-middle decryption Apache Tomcat Native (tcnative), the optional library that lets Tomcat handle TLS via OpenSSL through the APR/native connector, initialized its SSL context with insecure defaults, enabling ALLOW_CLIENT_RENEGOTIATION, NO_EXTENDED_MASTER_SECRET, IGNORE_UNEXPECTED_EOF, and ALLOW_NO_DHE_KEX. A network attacker in a man-in-the-middle position can leverage these weakened settings — for example renegotiation and triple-handshake-style attacks, loss of forward secrecy, and ignored truncation — to decrypt or tamper with TLS traffic between clients and an affected server. Impact is rated critical (CVSS 9.1) with high confidentiality and integrity impact but no availability impact. Deployments affected are those running Tomcat with Tomcat Native 2.0.0–2.0.15 or 1.3.0–1.3.8 (earlier unsupported versions may also be affected); Tomcat instances using the default Java JSSE/NIO connectors are not exposed to this library's defaults. There is no known public exploit and the issue is not on the CISA KEV, but it is a config-level flaw that silently weakens TLS for every affected deployment. |
Posted by Mark Thomas on Sep 23 Severity: moderate Affected versions: - Apache Tomcat Native 2.0.0 through 2.0.15 - Apache Tomcat Native 1.3.0 through 1.3.8 Description: Initialization of a resource with an insecure default vulnerability in Apache Tomcat Native enabled insecure options by default including ALLOW_CLIENT_RENEGOTIATION, NO_EXTENDED_MASTER_SECRET, IGNORE_UNEXPECTED_EOF and ALLOW_NO_DHE_KEX. This issue affects Apache Tomcat Native: from 2.0.0 through...
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