Vulnerability-Lookup

CVE-2026-49753 (GCVE-0-2026-49753)

Vulnerability from cvelistv5 – Published: 2026-06-02 14:15 – Updated: 2026-06-02 19:14

Title

HTTP response smuggling in Mint HTTP/1 client via lenient Content-Length parsing

Summary

Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') vulnerability in elixir-mint Mint allows attacker-controlled HTTP/1 servers to desynchronise response framing on shared connections. Mint's HTTP/1 Content-Length parser, Mint.HTTP1.Parse.content_length_header/1 in lib/mint/http1/parse.ex, parses the header value with Integer.parse/1, which accepts an optional + or - sign prefix. The length >= 0 guard rejects negatives, but inputs such as +0 or +123 are returned as valid lengths. RFC 7230 specifies Content-Length = 1*DIGIT, with no sign character permitted. A fronting proxy or load balancer that strictly enforces the grammar will reject or reframe a header like Content-Length: +0, while Mint silently treats it as zero. When Mint reuses the socket (keep-alive, pipelining, or any pooled connection shared across requesters), the parser disagreement is a response-smuggling primitive: the proxy delimits the body one way, Mint another, and bytes from one response get attributed to the next. Where the same Mint connection is shared across trust boundaries, an attacker-controlled upstream can leak bytes into a different consumer's response stream. This issue affects mint: from 0.1.0 before 1.9.0.

Severity

6.3 (Medium)


                        
                          CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/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

4 references

URL	Tags
https://github.com/elixir-mint/mint/security/advi…	vendor-advisoryrelated
https://cna.erlef.org/cves/CVE-2026-49753.html	related
https://osv.dev/vulnerability/EEF-CVE-2026-49753	related
https://github.com/elixir-mint/mint/commit/47e480…	patch

Impacted products

2 products

Vendor	Product	Version
elixir-mint	mint	Affected: 0.1.0 , < 1.9.0 (semver) cpe:2.3:a:elixir-mint:mint::::::::
elixir-mint	mint	Affected: 65e0e86d799a6d3b08e4372fccdd9747535e0dd6 , < 47e48027480228e4e32a0b4df39db497b4804921 (git) cpe:2.3:a:elixir-mint:mint::::::::

Credits

Peter Ullrich Eric Meadows-Jönsson Jonatan Männchen / EEF

Show details on NVD website

JSON

To clipboard

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The \u003ctt\u003elength \u0026gt;= 0\u003c/tt\u003e guard rejects negatives, but inputs such as \u003ctt\u003e+0\u003c/tt\u003e or \u003ctt\u003e+123\u003c/tt\u003e are returned as valid lengths. RFC 7230 specifies \u003ctt\u003eContent-Length = 1*DIGIT\u003c/tt\u003e, with no sign character permitted.\u003c/p\u003e\u003cp\u003eA fronting proxy or load balancer that strictly enforces the grammar will reject or reframe a header like \u003ctt\u003eContent-Length: +0\u003c/tt\u003e, while Mint silently treats it as zero. When Mint reuses the socket (keep-alive, pipelining, or any pooled connection shared across requesters), the parser disagreement is a response-smuggling primitive: the proxy delimits the body one way, Mint another, and bytes from one response get attributed to the next. Where the same Mint connection is shared across trust boundaries, an attacker-controlled upstream can leak bytes into a different consumer\u0027s response stream.\u003c/p\u003e\u003cp\u003eThis issue affects mint: from 0.1.0 before 1.9.0.\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)\"}]}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"1.9.0\", \"versionStartIncluding\": \"0.1.0\"}], \"operator\": \"OR\"}], \"operator\": \"AND\"}], \"providerMetadata\": {\"orgId\": \"6b3ad84c-e1a6-4bf7-a703-f496b71e49db\", \"shortName\": \"EEF\", \"dateUpdated\": \"2026-06-02T19:14:42.817Z\"}}}",
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}

FKIE_CVE-2026-49753

Vulnerability from fkie_nvd - Published: 2026-06-02 16:16 - Updated: 2026-07-22 19:10

Severity

6.3 (Medium) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

Summary

References

	URL	Tags
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://cna.erlef.org/cves/CVE-2026-49753.html
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/elixir-mint/mint/commit/47e48027480228e4e32a0b4df39db497b4804921
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://github.com/elixir-mint/mint/security/advisories/GHSA-mjqx-c6f6-7rc2
	6b3ad84c-e1a6-4bf7-a703-f496b71e49db	https://osv.dev/vulnerability/EEF-CVE-2026-49753
	134c704f-9b21-4f2e-91b3-4a467353bcc0	https://github.com/elixir-mint/mint/security/advisories/GHSA-mjqx-c6f6-7rc2

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://repo.hex.pm",
          "cpes": [
            "cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Mint.HTTP1.Parse\u0027"
          ],
          "packageName": "mint",
          "packageURL": "pkg:hex/mint",
          "product": "mint",
          "programFiles": [
            "lib/mint/http1/parse.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Mint.HTTP1.Parse\u0027:content_length_header/1"
            }
          ],
          "repo": "https://github.com/elixir-mint/mint",
          "vendor": "elixir-mint",
          "versions": [
            {
              "lessThan": "1.9.0",
              "status": "affected",
              "version": "0.1.0",
              "versionType": "semver"
            }
          ]
        },
        {
          "collectionURL": "https://github.com",
          "cpes": [
            "cpe:2.3:a:elixir-mint:mint:*:*:*:*:*:*:*:*"
          ],
          "defaultStatus": "unaffected",
          "modules": [
            "\u0027Elixir.Mint.HTTP1.Parse\u0027"
          ],
          "packageName": "elixir-mint/mint",
          "packageURL": "pkg:github/elixir-mint/mint",
          "product": "mint",
          "programFiles": [
            "lib/mint/http1/parse.ex"
          ],
          "programRoutines": [
            {
              "name": "\u0027Elixir.Mint.HTTP1.Parse\u0027:content_length_header/1"
            }
          ],
          "repo": "https://github.com/elixir-mint/mint.git",
          "vendor": "elixir-mint",
          "versions": [
            {
              "lessThan": "47e48027480228e4e32a0b4df39db497b4804921",
              "status": "affected",
              "version": "65e0e86d799a6d3b08e4372fccdd9747535e0dd6",
              "versionType": "git"
            }
          ]
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "Inconsistent Interpretation of HTTP Requests (\u0027HTTP Request/Response Smuggling\u0027) vulnerability in elixir-mint Mint allows attacker-controlled HTTP/1 servers to desynchronise response framing on shared connections.\n\nMint\u0027s HTTP/1 Content-Length parser, Mint.HTTP1.Parse.content_length_header/1 in lib/mint/http1/parse.ex, parses the header value with Integer.parse/1, which accepts an optional + or - sign prefix. The length \u003e= 0 guard rejects negatives, but inputs such as +0 or +123 are returned as valid lengths. RFC 7230 specifies Content-Length = 1*DIGIT, with no sign character permitted.\n\nA fronting proxy or load balancer that strictly enforces the grammar will reject or reframe a header like Content-Length: +0, while Mint silently treats it as zero. When Mint reuses the socket (keep-alive, pipelining, or any pooled connection shared across requesters), the parser disagreement is a response-smuggling primitive: the proxy delimits the body one way, Mint another, and bytes from one response get attributed to the next. Where the same Mint connection is shared across trust boundaries, an attacker-controlled upstream can leak bytes into a different consumer\u0027s response stream.\n\nThis issue affects mint: from 0.1.0 before 1.9.0."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad de \u0027Interpretaci\u00f3n inconsistente de solicitudes HTTP\u0027 (\u0027Contrabando de Solicitudes/Respuestas HTTP\u0027) en elixir-mint Mint permite a servidores HTTP/1 controlados por el atacante desincronizar el enmarcado de respuestas en conexiones compartidas.\n\nEl analizador Content-Length HTTP/1 de Mint, Mint.HTTP1.Parse.content_length_header/1 en lib/mint/http1/parse.ex, analiza el valor del encabezado con Integer.parse/1, que acepta un prefijo de signo + o - opcional. La guarda length \u003e= 0 rechaza los negativos, pero entradas como +0 o +123 se devuelven como longitudes v\u00e1lidas. RFC 7230 especifica Content-Length = 1DIGIT, sin permitir ning\u00fan car\u00e1cter de signo.\n\nUn proxy frontal o balanceador de carga que aplica estrictamente la gram\u00e1tica rechazar\u00e1 o reenmarcar\u00e1 un encabezado como Content-Length: +0, mientras que Mint lo trata silenciosamente como cero. Cuando Mint reutiliza el socket (keep-alive, pipelining, o cualquier conexi\u00f3n agrupada compartida entre solicitantes), el desacuerdo del analizador es una primitiva de contrabando de respuestas: el proxy delimita el cuerpo de una manera, Mint de otra, y los bytes de una respuesta se atribuyen a la siguiente. Donde la misma conexi\u00f3n de Mint se comparte a trav\u00e9s de l\u00edmites de confianza, un upstream controlado por el atacante puede filtrar bytes en el flujo de respuesta de un consumidor diferente.\n\nEste problema afecta a mint: desde 0.1.0 antes de 1.9.0."
    }
  ],
  "id": "CVE-2026-49753",
  "lastModified": "2026-07-22T19:10:00.120",
  "metrics": {
    "cvssMetricV40": [
      {
        "cvssData": {
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "attackComplexity": "LOW",
          "attackRequirements": "PRESENT",
          "attackVector": "NETWORK",
          "availabilityRequirement": "NOT_DEFINED",
          "baseScore": 6.3,
          "baseSeverity": "MEDIUM",
          "confidentialityRequirement": "NOT_DEFINED",
          "exploitMaturity": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "privilegesRequired": "NONE",
          "providerUrgency": "NOT_DEFINED",
          "subAvailabilityImpact": "NONE",
          "subConfidentialityImpact": "LOW",
          "subIntegrityImpact": "LOW",
          "userInteraction": "NONE",
          "valueDensity": "NOT_DEFINED",
          "vectorString": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "version": "4.0",
          "vulnAvailabilityImpact": "NONE",
          "vulnConfidentialityImpact": "NONE",
          "vulnIntegrityImpact": "LOW",
          "vulnerabilityResponseEffort": "NOT_DEFINED"
        },
        "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-49753",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-06-02T18:06:41.525477Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-06-02T16:16:44.777",
  "references": [
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://cna.erlef.org/cves/CVE-2026-49753.html"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/elixir-mint/mint/commit/47e48027480228e4e32a0b4df39db497b4804921"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://github.com/elixir-mint/mint/security/advisories/GHSA-mjqx-c6f6-7rc2"
    },
    {
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-49753"
    },
    {
      "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
      "url": "https://github.com/elixir-mint/mint/security/advisories/GHSA-mjqx-c6f6-7rc2"
    }
  ],
  "sourceIdentifier": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
  "vulnStatus": "Deferred",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-444"
        }
      ],
      "source": "6b3ad84c-e1a6-4bf7-a703-f496b71e49db",
      "type": "Secondary"
    }
  ]
}

GHSA-MJQX-C6F6-7RC2

Vulnerability from github – Published: 2026-07-09 23:19 – Updated: 2026-07-09 23:19

Summary

mint: Content-Length header accepts non-RFC "+" sign prefix

Details

Summary

Mint's HTTP/1 client accepts Content-Length header values with a leading + sign (e.g. +0, +123), which RFC 7230 forbids (Content-Length = 1*DIGIT). On a connection shared with a strict fronting proxy or load balancer, this parser disagreement is a response-smuggling primitive: the proxy frames the body one way, Mint frames it another, and bytes meant for one response leak into the next consumer's response stream.

Details

'Elixir.Mint.HTTP1.Parse':content_length_header/1 in lib/mint/http1/parse.ex parses the header value with Integer.parse/1. By design, Integer.parse/1 accepts an optional + or - sign prefix. The length >= 0 guard rules out negatives, but inputs such as "+0", "+123", or "+1" pass through and are returned as valid lengths.

A strict proxy or load balancer rejects or reframes Content-Length: +0\r\n, while Mint silently treats it as 0. When Mint reuses the socket (keep-alive, pipelining, or any pooled connection) and the connection is shared with a proxy that frames the same bytes differently, trailing bytes the proxy attributes to response N are attributed by Mint to response N+1. Across trust boundaries (shared pools, multi-tenant fronting) this enables response smuggling.

PoC

Stand up a raw TCP server that returns HTTP/1.1 200 OK\r\nContent-Length: +0\r\nConnection: keep-alive\r\n\r\n<smuggled bytes>.
Connect a Mint HTTP/1 client to the server and issue a request.
Observe that Mint reports the response as status 200 with Content-Length: "+0" and an empty body, leaving the smuggled bytes sitting in the socket buffer for the next response.

Impact

Response-smuggling / request-response desync primitive in Mint's HTTP/1 client parser. Anyone using Mint (directly or via Finch, Tesla's Mint adapter, Req, etc.) to talk through a shared or pooled connection where a fronting proxy enforces RFC 7230 strictly while Mint does not is exposed. The attacker is the response producer (a malicious or compromised upstream, or anything that can inject bytes into a shared origin response); exploitation into a cross-request data leak additionally requires the deployment to share a Mint connection across trust boundaries.

Resources

Introduction commit: https://github.com/elixir-mint/mint/commit/65e0e86d799a6d3b08e4372fccdd9747535e0dd6
Patch commit: https://github.com/elixir-mint/mint/commit/47e48027480228e4e32a0b4df39db497b4804921

Severity

6.3 (Medium)


                  
                    CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "Hex",
        "name": "mint"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.9.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-49753"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-444"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-07-09T23:19:16Z",
    "nvd_published_at": "2026-06-02T16:16:44Z",
    "severity": "MODERATE"
  },
  "details": "### Summary\n\nMint\u0027s HTTP/1 client accepts `Content-Length` header values with a leading `+` sign (e.g. `+0`, `+123`), which RFC 7230 forbids (`Content-Length = 1*DIGIT`). On a connection shared with a strict fronting proxy or load balancer, this parser disagreement is a response-smuggling primitive: the proxy frames the body one way, Mint frames it another, and bytes meant for one response leak into the next consumer\u0027s response stream.\n\n### Details\n\n`\u0027Elixir.Mint.HTTP1.Parse\u0027:content_length_header/1` in `lib/mint/http1/parse.ex` parses the header value with `Integer.parse/1`. By design, `Integer.parse/1` accepts an optional `+` or `-` sign prefix. The `length \u003e= 0` guard rules out negatives, but inputs such as `\"+0\"`, `\"+123\"`, or `\"+1\"` pass through and are returned as valid lengths.\n\nA strict proxy or load balancer rejects or reframes `Content-Length: +0\\r\\n`, while Mint silently treats it as `0`. When Mint reuses the socket (keep-alive, pipelining, or any pooled connection) and the connection is shared with a proxy that frames the same bytes differently, trailing bytes the proxy attributes to response N are attributed by Mint to response N+1. Across trust boundaries (shared pools, multi-tenant fronting) this enables response smuggling.\n\n### PoC\n\n1. Stand up a raw TCP server that returns `HTTP/1.1 200 OK\\r\\nContent-Length: +0\\r\\nConnection: keep-alive\\r\\n\\r\\n\u003csmuggled bytes\u003e`.\n2. Connect a Mint HTTP/1 client to the server and issue a request.\n3. Observe that Mint reports the response as status 200 with `Content-Length: \"+0\"` and an empty body, leaving the smuggled bytes sitting in the socket buffer for the next response.\n\n### Impact\n\nResponse-smuggling / request-response desync primitive in Mint\u0027s HTTP/1 client parser. Anyone using Mint (directly or via Finch, Tesla\u0027s Mint adapter, Req, etc.) to talk through a shared or pooled connection where a fronting proxy enforces RFC 7230 strictly while Mint does not is exposed. The attacker is the response producer (a malicious or compromised upstream, or anything that can inject bytes into a shared origin response); exploitation into a cross-request data leak additionally requires the deployment to share a Mint connection across trust boundaries.\n\n## Resources\n\n* Introduction commit: https://github.com/elixir-mint/mint/commit/65e0e86d799a6d3b08e4372fccdd9747535e0dd6\n* Patch commit: https://github.com/elixir-mint/mint/commit/47e48027480228e4e32a0b4df39db497b4804921",
  "id": "GHSA-mjqx-c6f6-7rc2",
  "modified": "2026-07-09T23:19:17Z",
  "published": "2026-07-09T23:19:16Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/elixir-mint/mint/security/advisories/GHSA-mjqx-c6f6-7rc2"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-49753"
    },
    {
      "type": "WEB",
      "url": "https://github.com/elixir-mint/mint/commit/47e48027480228e4e32a0b4df39db497b4804921"
    },
    {
      "type": "WEB",
      "url": "https://cna.erlef.org/cves/CVE-2026-49753.html"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/elixir-mint/mint"
    },
    {
      "type": "WEB",
      "url": "https://osv.dev/vulnerability/EEF-CVE-2026-49753"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:N/SC:L/SI:L/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "mint: Content-Length header accepts non-RFC \"+\" sign prefix"
}

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.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.

Action not permitted

CVE-2026-49753 (GCVE-0-2026-49753)

FKIE_CVE-2026-49753

GHSA-MJQX-C6F6-7RC2

Summary

Details

PoC

Impact

Resources

Tags

Sightings

Nomenclature