CVE-2026-41873:

CVE-2026-41873 is a critical HTTP Request/Response Smuggling vulnerability (CWE-444) in the Lua implementation of Apache Pony Mail that can lead to complete admin account takeover. All versions of the Lua implementation are affected, and no fix will be released as the project is retired.

Score
A numerical rating that indicates how dangerous this vulnerability is.

9.8Critical

Published Date:Apr 28, 2026
CISA KEV Date:*No Data*
Industries Affected:20

Exploitability

Score:3.9
Attack Vector:NETWORK
Attack Complexity:LOW
Privileges Required:NONE
User Interaction:NONE
Scope:UNCHANGED

Impact

Score:5.9
Confidentiality Impact:HIGH
Integrity Impact:HIGH
Availability Impact:HIGH

Description Preview

Overview

CVE-2026-41873 is a critical-severity HTTP smuggling vulnerability affecting the Lua implementation of Apache Pony Mail across all released versions. The flaw arises from inconsistent interpretation of HTTP requests (CWE-444), a class of vulnerability where differences in how front-end and back-end systems parse HTTP message boundaries can be exploited to inject or manipulate requests. In this case, successful exploitation allows an unauthenticated attacker over the network to perform an admin account takeover, achieving full compromise of confidentiality, integrity, and availability of the application. The Apache Security Team has tagged this vulnerability as "unsupported when assigned," as the Lua implementation of Pony Mail has been retired and will not receive a security patch. Organizations still running this software are exposed to a high-severity risk with no vendor-supplied remediation path available.

Remediation

Because the Lua implementation of Apache Pony Mail is retired and the maintainers have explicitly stated that no fix will be produced, there is no patch or updated version available to address this vulnerability. Affected users are advised to migrate away from the Lua-based Pony Mail deployment at the earliest opportunity. As an interim measure, access to any running Pony Mail Lua instances should be immediately restricted to trusted users only, such as through network-level controls, firewall rules, or VPN-based access restrictions, to reduce exposure. Organizations should monitor the development progress of the Python-based replacement, Pony Mail Foal, as a potential migration target, though it has not yet been officially released. In the meantime, evaluating alternative mailing list archive solutions is strongly recommended.