This High severity BASM (Broken Authentication & Session Management) vulnerability was introduced in version 4.9.0 of Crucible Server.

This BASM (Broken Authentication & Session Management) vulnerability, with a CVSS Score of 8.7 and a CVSS Vector of CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N allows an unauthenticated attacker to perform actions as another user.

Atlassian recommends that Crucible Server customers upgrade to latest version, if you are unable to do so, upgrade your instance to one of the specified supported fixed versions:

• Crucible Server 4.9: Upgrade to a release greater than or equal to 4.9.13

See the release notes (https://confluence.atlassian.com/crucible/crucible-releases-298977378.html). You can download the latest version of Crucible Server from the download center (https://www.atlassian.com/software/crucible/download-archives).

The National Vulnerability Database provides the following description for this vulnerability: In Eclipse Jetty, the Digest authentication server-side component uses ISO-8859-1 to encode the password as bytes.

This was done because the initial specification for HTTP did not specify explicitly a charset, and it was assumed to be ISO-8859-1 for historical reasons.

If the password contains characters that cannot be represented in ISO-8859-1, they are silently replaced by `?`. This happens with passwords that contain Chinese, Cyrillic or Greek characters, for example: `αβ123` converts to `??123`.

An attacker can send a request with a digest `Authorization` header crafted with a password made of only `?` characters; the server would match any password of the same length that contains non-ISO-8859-1 characters.

Recent HTTP Digest [RFC-7616](https://datatracker.ietf.org/doc/html/rfc7616) supports a `charset` parameters that defaults to UTF-8 that allows for correct encoding/decoding of passwords.