OPT: Update dependency zeep to v4.3.3 [SECURITY]

[renovate]

This PR contains the following updates:

Package	Change	Age	Adoption	Passing	Confidence
zeep (changelog)	4.3.1 → 4.3.3

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Zeep: Server-Side Request Forgery (SSRF)

GHSA-4cc2-g9w2-fhf6

More information

Details

Summary

When parsing a WSDL or XSD document, python-zeep follows transitive references — xsd:import, xsd:include, wsdl:import, and lxml entity/DTD resolution — and will fetch http/https URLs found in those references. The Settings.forbid_external option, intended to disable this transitive remote fetching, was defined but not wired to any logic from version 4.0.0 through 4.3.2 (a regression introduced when zeep moved off defusedxml in 4.0). As a result, setting forbid_external=True had no effect, and applications that processed untrusted or attacker-influenced WSDL/XSD documents could be coerced into making server-side requests to arbitrary URLs (SSRF).

Impact

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

An attacker who can supply or influence the contents of a WSDL/XSD that an application loads with zeep can embed an import/include reference (e.g. <xsd:import schemaLocation="http://169.254.169.254/...">) pointing at an internal or otherwise sensitive endpoint. When zeep parses the document it transitively fetches that URL using the configured transport, causing the application to issue outbound requests to attacker-chosen destinations. This can be used to reach internal-only services, cloud metadata endpoints, or other hosts not directly reachable by the attacker, and may disclose response timing/behaviour.

Impacted users are those who:

• load WSDL/XSD documents that are untrusted or whose import targets an attacker can control, and/or
• relied on forbid_external=True as a security control — in 4.0.0–4.3.2 that setting silently did nothing, so the protection users believed they had was not in effect.

Note the default was (and remains) forbid_external=False, i.e. transitive remote fetching is permitted by default; the security defect is specifically that the opt-out control was non-functional.

Patches

Fixed in python-zeep 4.3.3. The forbid_external setting is now enforced: when set to True, zeep refuses to transitively fetch http/https resources via xsd:import, xsd:include, wsdl:import, or lxml entity/DTD resolution, raising zeep.exceptions.ExternalReferenceForbidden. The user-supplied entry-point WSDL/schema URL is still loaded.

Affected versions: >= 4.0.0, < 4.3.3.

Upgrade to 4.3.3 (or later) and set forbid_external=True when loading documents from untrusted sources:

from zeep import Client, Settings

settings = Settings(forbid_external=True)
client = Client("https://untrusted.example/service?wsdl", settings=settings)

Workarounds

If you cannot upgrade to 4.3.3:

• Do not load untrusted WSDL/XSD documents, and avoid loading WSDLs whose import/include targets can be influenced by untrusted input.
• Vendor the schema locally: pre-fetch and review the WSDL and all of its imported schemas, then load them from local files (e.g. file:// paths) so no remote fetching occurs at parse
  time.
• Restrict egress at the network layer: block outbound traffic from the host/process to internal ranges and metadata endpoints (e.g. 169.254.169.254, RFC1918 ranges) so SSRF attempts
  cannot reach sensitive targets.
• Use a restrictive custom Transport: subclass the zeep transport and reject/allow-list URLs in load() so disallowed hosts are never fetched.

Severity

• CVSS Score: 5.9 / 10 (Medium)
• Vector String: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

References

• https://github.com/mvantellingen/python-zeep/security/advisories/GHSA-4cc2-g9w2-fhf6
• https://github.com/mvantellingen/python-zeep/commit/83eb07bc6c84d841329d4f88856fecdba86f753e
• https://github.com/mvantellingen/python-zeep/releases/tag/4.3.3
• https://github.com/advisories/GHSA-4cc2-g9w2-fhf6

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

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Release Notes

mvantellingen/python-zeep (zeep)

v4.3.3

Compare Source

• Wire up the forbid_external setting (previously defined but unused
  since the move off defusedxml in 4.0). When enabled it refuses to
  transitively fetch http/https resources via xsd:import,
  xsd:include, wsdl:import or lxml entity resolution, raising
  zeep.exceptions.ExternalReferenceForbidden. The user-supplied
  entry-point WSDL/schema URL is still loaded. The default remains
  False to preserve existing behaviour; enable when loading WSDLs from
  untrusted sources to mitigate SSRF via attacker-controlled import
  targets.
• Internal tooling only: migrate dependency/build management to uv and
  replace isort/flake8/black with ruff. No runtime changes.

v4.3.2

Compare Source

• Support newer versions of httpx (#​1447)

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.70%. Comparing base (085c4a6) to head (c3786d6).

Additional details and impacted files

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  Coverage   92.70%   92.70%           
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  Files          33       33           
  Lines         891      891           
  Branches       49       49           
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  Hits          826      826           
  Misses         47       47           
  Partials       18       18           

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