Jenkins Git server Plugin 99.va_0826a_b_cdfa_d and earlier does not disable a feature of its command parser that replaces an '@' character followed by a file…

Jenkins Git server Plugin 99.va_0826a_b_cdfa_d and earlier does not disable a feature of its command parser that replaces an '@' character followed by a file path in an argument with the file's contents, allowing attackers with Overall/Read permission to read content from arbitrary files on the Jenkins controller file system.