SB20260921153 - Red Hat Enterprise Linux 8 update for tomcat
Published: September 21, 2026 Updated: September 30, 2026
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 8 vulnerabilities.
1) Improper Authentication (CVE-ID: CVE-2026-43512)
CWE-ID: CWE-287 - Improper Authentication
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to authenticate as an unknown user.
The vulnerability exists due to improper authentication in the DIGEST authenticator when processing authentication for users not known to the configured Realm. A remote attacker can submit the password "null" for an unknown user to authenticate as an unknown user.
This occurs only when DIGEST authentication is configured.
2) Input validation error (CVE-ID: CVE-2026-41293)
CWE-ID: CWE-20 - Improper input validation
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to trigger unexpected application behavior.
The vulnerability exists due to improper input validation in HTTP/2 request header handling when exposing header values through the Servlet API. A remote attacker can send crafted HTTP/2 request headers to trigger unexpected application behavior.
This may affect applications that assume header values exposed through the Servlet API are specification compliant.
3) Information disclosure (CVE-ID: CVE-2026-42498)
CWE-ID: CWE-200 - Exposure of sensitive information to an unauthorized actor
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to disclose authentication headers to a redirect target host.
The vulnerability exists due to exposure of sensitive information in Tomcat's WebSocket client when following a redirected WebSocket request after authentication. A remote user can trigger a redirect after authentication to disclose authentication headers to a redirect target host.
The issue occurs only if a WebSocket request is redirected after authentication.
4) Improper access control (CVE-ID: CVE-2026-43515)
CWE-ID: CWE-284 - Improper Access Control
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass security constraints.
The vulnerability exists due to improper access control in HTTP method constraint processing when evaluating multiple security constraints for the same extension pattern. A remote attacker can send a request using an improperly constrained HTTP method to bypass security constraints.
5) Improper Handling of Case Sensitivity (CVE-ID: CVE-2026-43513)
CWE-ID: CWE-178 - Improper Handling of Case Sensitivity
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to weaken brute-force protection against a user's password.
The vulnerability exists due to improper input handling in LockOutRealm when processing case-insensitive user names. A remote attacker can vary the case of a user name during authentication attempts to weaken brute-force protection against a user's password.
This affects Realms where user names are treated as case insensitive.
6) Improper authentication (CVE-ID: CVE-2026-55957)
CWE-ID: CWE-287 - Improper Authentication
CVSSv4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass authentication.
The vulnerability exists due to improper authentication in JNDIRealm when authenticating binds using GSSAPI. A remote attacker can authenticate without providing the correct password to bypass authentication.
7) Incorrect Behavior Order: Validate Before Canonicalize (CVE-ID: CVE-2026-59083)
CWE-ID: CWE-180 - Incorrect Behavior Order: Validate Before Canonicalize
CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote attacker to bypass security controls.
The vulnerability exists due to incorrect URL decoding in RewriteValve when processing rewritten URIs. A remote attacker can send a specially crafted request to bypass security controls.
Only some configurations are vulnerable.
8) Insufficient Technical Documentation (CVE-ID: CVE-2026-59084)
CWE-ID: CWE-1059 - Insufficient Technical Documentation
CVSSv4: 2.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to bypass encryption protections.
The vulnerability exists due to improper documentation in EncryptInterceptor configuration when deploying the feature. A remote user can leverage an insecure configuration to bypass encryption protections.
Remediation
Install update from vendor's website.