CVE-2026-94194

Mint HTTP/1 client applies chunked framing when chunked is not the final transfer coding, enabling response smuggling through intermediaries

Published Sep 28, 2026 CVSS 4.0 · 6.3 Medium EPSS < 1% KEV · Not listed
Description
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize an intermediary and the Mint client on a pooled connection, poisoning the responses to subsequent requests that share the connection.

message_body/1 in lib/mint/http1.ex selects chunked framing when chunked is the first coding listed in a response's Transfer-Encoding fields. RFC 9112 section 6.3 applies chunked framing only when chunked is the final coding, and otherwise reads the body until the server closes the connection. For a response such as Transfer-Encoding: chunked, gzip, an intermediary that follows the RFC treats every byte up to the close as the body, while Mint ends the body at the zero-length chunk and parses the remaining bytes as the response to the next request on the connection.

Mint also keeps the connection open after an HTTP/1.0 response, final or 1xx, that carries Transfer-Encoding and Connection: keep-alive. RFC 9112 section 6.1 requires treating the framing of such a message as faulty and closing the connection after it, so bytes after its chunked body are parsed as the response to the next request in the same way.

This issue affects mint: from 0.1.0 before 1.10.2.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

No advisories available
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
Description Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize an intermediary and the Mint client on a pooled connection, poisoning the responses to subsequent requests that share the connection. message_body/1 in lib/mint/http1.ex selects chunked framing when chunked is the first coding listed in a response's Transfer-Encoding fields. RFC 9112 section 6.3 applies chunked framing only when chunked is the final coding, and otherwise reads the body until the server closes the connection. For a response such as Transfer-Encoding: chunked, gzip, an intermediary that follows the RFC treats every byte up to the close as the body, while Mint ends the body at the zero-length chunk and parses the remaining bytes as the response to the next request on the connection. Mint also keeps the connection open after an HTTP/1.0 response, final or 1xx, that carries Transfer-Encoding and Connection: keep-alive. RFC 9112 section 6.1 requires treating the framing of such a message as faulty and closing the connection after it, so bytes after its chunked body are parsed as the response to the next request in the same way. This issue affects mint: from 0.1.0 before 1.11.0. Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize an intermediary and the Mint client on a pooled connection, poisoning the responses to subsequent requests that share the connection. message_body/1 in lib/mint/http1.ex selects chunked framing when chunked is the first coding listed in a response's Transfer-Encoding fields. RFC 9112 section 6.3 applies chunked framing only when chunked is the final coding, and otherwise reads the body until the server closes the connection. For a response such as Transfer-Encoding: chunked, gzip, an intermediary that follows the RFC treats every byte up to the close as the body, while Mint ends the body at the zero-length chunk and parses the remaining bytes as the response to the next request on the connection. Mint also keeps the connection open after an HTTP/1.0 response, final or 1xx, that carries Transfer-Encoding and Connection: keep-alive. RFC 9112 section 6.1 requires treating the framing of such a message as faulty and closing the connection after it, so bytes after its chunked body are parsed as the response to the next request in the same way. This issue affects mint: from 0.1.0 before 1.10.2.
References
Type Values Removed Values Added
Description Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize an intermediary and the Mint client on a pooled connection, poisoning the responses to subsequent requests that share the connection. message_body/1 in lib/mint/http1.ex selects chunked framing when chunked is the first coding listed in a response's Transfer-Encoding fields. RFC 9112 section 6.3 applies chunked framing only when chunked is the final coding, and otherwise reads the body until the server closes the connection. For a response such as Transfer-Encoding: chunked, gzip, an intermediary that follows the RFC treats every byte up to the close as the body, while Mint ends the body at the zero-length chunk and parses the remaining bytes as the response to the next request on the connection. Mint also keeps the connection open after an HTTP/1.0 response, final or 1xx, that carries Transfer-Encoding and Connection: keep-alive. RFC 9112 section 6.1 requires treating the framing of such a message as faulty and closing the connection after it, so bytes after its chunked body are parsed as the response to the next request in the same way. This issue affects mint: from 0.1.0 before 1.11.0.
Title Mint HTTP/1 client applies chunked framing when chunked is not the final transfer coding, enabling response smuggling through intermediaries
First Time appeared Elixir-mint
Elixir-mint mint
Weaknesses CWE-444
CPEs cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*
Vendors & Products Elixir-mint
Elixir-mint mint
References
Metrics cvssV4_0

{'score': 6.3, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
EEF
Published
Updated
Sep 30, 2026, 1:17 PM
Reserved
Sep 24, 2026, 1:45 PM
Status
Deferred
Published
Sep 28, 2026, 12:17 PM
Modified
Sep 30, 2026, 2:17 PM