In ServerCo getssl version 2.49 and prior, the ACME challenge token returned to the client was not strictly validated against RFC 8555 before being used in challenge-file handling, allowing a maliciously crafted token to influence local path/filename usage during validation. An attacker who can supply ACME challenge responses to getssl (for example, a malicious or compromised CA endpoint, or an on-path adversary able to tamper with that response path) could exploit this to achieve unauthorized file write/path traversal effects, usually with elevated privileges, ultimately allowing for remote command injection. This issue appears related in spirit to CVE-2023-38198, and is an instance of CWE-73, "External control of file name or path." Other ACME shell script handlers may be affected by similar issues.
Exploitability
AV:NAC:HPR:NUI:NScope
S:UImpact
C:HI:HA:N7.4/CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:NInput Validation