CVE intelligence and bounded remediation

CVE-2026-41873 — Apache Pony Mail security vulnerability

Critical CVSS 9.8

** UNSUPPORTED WHEN ASSIGNED ** Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in Pony Mail leading to admin account takeover. This issue affects all versions of the Lua implementation of Pony Mail. There is a Python implementation under development under the name "Pony Mail Foal" that is not affected by this issue, but hasn't been released yet. As the Lua implementation of this project is retired, we do not plan to release a version that fixes this issue. Users are recommended to find an alternative or restrict access to the instance to trusted users. NOTE: This vulnerability only affects products that are no longer supported by the maintainer.

Severity
Critical
CVSS
9.8 (3.1)
Published
2026-04-28
CISA KEV
Not currently listed
Ecosystem
python/pypi
Weaknesses
CWE-444

Affected products

  • apache / pony_mail

Matched remediation archetype

HTTP request smuggling and message-boundary ambiguity

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Check exposure

  • Inventory every proxy, CDN, gateway, load balancer, service mesh, and application server hop on affected request paths.
  • Compare documented parsing and normalization behavior for message length, transfer coding, duplicate headers, and protocol translation.
  • Identify connection reuse and which downstream services trust headers added by intermediaries.

Remediate safely

  • Update affected intermediaries and origin servers and align them on a single standards-compliant request framing policy.
  • Reject ambiguous length, transfer-coding, duplicate, malformed, and unsupported framing before forwarding.
  • Normalize or remove hop-by-hop and identity headers at one controlled boundary and add multi-hop regression tests.

Authoritative sources

Complete CVE record and remediation plan

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