SECURITY UPDATE: JNDIRealm bypass when configured with GSSAPI
authentication - HttpServletRequest.login(username, password) calls
validated credentials via the GSSAPI SASL mechanism instead of a
plain LDAP bind, silently accepting arbitrary passwords
debian/patches/CVE-2026-55957.patch: preserve DirContext
environment, drop the GSSAPI SECURITY_AUTHENTICATION setting
before the user-credential bind, and restore it in a finally
block via the existing restoreEnvironmentParameter() helper