CVE-2026-59249 (GCVE-0-2026-59249)

Vulnerability from cvelistv5 – Published: 2026-07-16 11:39 – Updated: 2026-07-17 10:11
VLAI
Title
Sign-tolerant HTTP/1 chunk-size parser in Mint enables response smuggling against strict intermediaries on pooled connections
Summary
Inconsistent interpretation of HTTP requests (HTTP response smuggling) vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize a strict intermediary and the Mint client on the same pooled connection, enabling response-queue poisoning against subsequent requests that share the connection. The Mint.HTTP1.decode_body/5 function in lib/mint/http1.ex parses the chunk-size line of a Transfer-Encoding: chunked response with Integer.parse(data, 16). RFC 7230 defines chunk-size = 1*HEXDIG and forbids any sign prefix, but Integer.parse/2 accepts an optional leading + or -. A chunk-size line of +5 is accepted as a five-byte chunk; lines of +0 and -0 are accepted as the terminating zero-length chunk and end the message body early. An RFC-strict intermediary in the response path rejects these forms, so the intermediary and the Mint client disagree on where one response ends and the next begins. On a pooled keep-alive connection, an attacker-influenced origin can inject bytes that the client attributes to the next legitimate response on the same connection, poisoning the response queue and corrupting the responses returned to unrelated in-flight requests. This issue affects mint: from 0.1.0 before 1.9.3.
Severity
6.3 (Medium)
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
SSVC
Exploitation: poc Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
  • CWE-444 - Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Assigner
EEF
References
Impacted products
Vendor Product Version
elixir-mint mint Affected: 0.1.0 , < 1.9.3 (semver)
    cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*
 Create a notification for this product.
elixir-mint mint Affected: 60089586ec7adc9fddb09f69a2f5919ba9ac7f33 , < fc7d16538db7e40b56ed489f08683225cb0197fa (git)
    cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*
 Create a notification for this product.
Credits
Thepigtails Andrea Leopardi Eric Meadows-Jönsson Jonatan Männchen / EEF
Show details on NVD website
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On a pooled keep-alive connection, an attacker-influenced origin can inject bytes that the client attributes to the next legitimate response on the same connection, poisoning the response queue and corrupting the responses returned to unrelated in-flight requests.\\n\\nThis issue affects mint: from 0.1.0 before 1.9.3.\", \"supportingMedia\": [{\"type\": \"text/html\", \"value\": \"\u003cp\u003eInconsistent interpretation of HTTP requests (HTTP response smuggling) vulnerability in elixir-mint mint allows a malicious HTTP/1 server to desynchronize a strict intermediary and the Mint client on the same pooled connection, enabling response-queue poisoning against subsequent requests that share the connection.\u003c/p\u003e\u003cp\u003eThe \u003ctt\u003eMint.HTTP1.decode_body/5\u003c/tt\u003e function in \u003ctt\u003elib/mint/http1.ex\u003c/tt\u003e parses the chunk-size line of a \u003ctt\u003eTransfer-Encoding: chunked\u003c/tt\u003e response with \u003ctt\u003eInteger.parse(data, 16)\u003c/tt\u003e. 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On a pooled keep-alive connection, an attacker-influenced origin can inject bytes that the client attributes to the next legitimate response on the same connection, poisoning the response queue and corrupting the responses returned to unrelated in-flight requests.\u003c/p\u003e\u003cp\u003eThis issue affects mint: from 0.1.0 before 1.9.3.\u003c/p\u003e\", \"base64\": false}]}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-444\", \"description\": \"CWE-444 Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027)\"}]}], \"configurations\": [{\"lang\": \"en\", \"value\": \"Exploitation requires a deployment topology in which an RFC-strict HTTP/1 intermediary (proxy, load balancer, or WAF) sits between the Mint client and the attacker-influenced origin, and HTTP/1 connections between the client and the intermediary are reused across requests (keep-alive with connection pooling). 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Mint clients that talk directly to an origin without an intermediary, or that do not reuse connections, are not exploitable for response-queue poisoning even if the vulnerable parsing behavior is present.\u003c/p\u003e\", \"base64\": false}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"1.9.3\", \"versionStartIncluding\": \"0.1.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-07-17T10:11:36.783Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2026-59249\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-07-17T10:11:36.783Z\", \"dateReserved\": \"2026-07-04T04:24:03.652Z\", \"assignerOrgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"datePublished\": \"2026-07-16T11:39:29.939Z\", \"assignerShortName\": \"EEF\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.