CVE-2026-10303

Summary

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 maliciou

Details

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.

References

• https://github.com/srvrco/getssl/pull/896
• https://github.com/srvrco/getssl/releases/tag/v2.50
• https://remyhax.xyz/posts/reproducing-lawful-tls-wiretapping/
• https://www.cve.org/CVERecord?id=CVE-2023-38198
• https://www.runzero.com/advisories/serverco-getssl-acme-cmd-injection-cve-2026-10303/