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High, CVSS 8.6amended

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

CVE-2026-33752GHSA-qw2m-4pqf-rmpp

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (curl-cffi 0.15.0), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS
8.6 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:N
EPSS
  • CVE-2026-33752: 0.48% estimated exploitation activity in the next 30 days; percentile 41.52 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

Summary curlcffi 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, curlcffi’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 curlcffi 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 (CURLOPTFOLLOWLOCATION = 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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 2 · amended ·

    Amended from ghsa record GHSA-qw2m-4pqf-rmpp

  2. Revision 1 · created ·

    Published from osv record GHSA-qw2m-4pqf-rmpp

Agent brief

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# Patch Next advisory brief: CVE-2026-33752

Advisory: curl_cffi: Redirect-based SSRF leads to internal network access in curl_cffi (with TLS impersonation bypass)
IDs: CVE-2026-33752, GHSA-qw2m-4pqf-rmpp
Record: https://patchnext.com/advisories/cve-2026-33752 (revision 2, source checked 26 Oct 2026, 13:40 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.6)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: curl-cffi 0.15.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI curl-cffi: affected < 0.15.0; fixed in 0.15.0

## Suggested inspection (read-only)
- `python -m pip show curl-cffi`: prints the installed version. Run with the environment that serves production active.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on curl-cffi.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-qw2m-4pqf-rmpp (OSV record GHSA-qw2m-4pqf-rmpp lists affected ranges: PyPI curl-cffi >=0 <0.15.0 (fixed))
- Verified: https://github.com/advisories/GHSA-qw2m-4pqf-rmpp (GitHub-reviewed advisory GHSA-qw2m-4pqf-rmpp lists affected ranges: PyPI curl-cffi >=0 <0.15.0)

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