datamodel-code-generator: Authorization / request headers leaked to cross-origin redirect target when fetching remote schemas

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

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

EPSS

• CVE-2026-55403: 0.34% estimated exploitation activity in the next 30 days; percentile 27.06 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary When datamodel-code-generator fetches a remote schema and follows an HTTP redirect, it re-sends the original request headers, including any Authorization header, to the redirect target even when the redirect changes origin (host/port/scheme). Credentials that an operator scoped to a trusted schema host are therefore forwarded to an attacker-controlled or otherwise different host, leaking them. Details In src/datamodelcodegenerator/http.py, getbody() follows redirects manually and re-issues each hop with the same headers argument, with no check that the origin is unchanged: Browsers and HTTP clients such as requests/httpx strip Authorization when a redirect crosses origin; here it is preserved unconditionally. Headers are operator-supplied via --http-headers (and credentials can also arrive through --url userinfo), so a redirect from the trusted host to any other host discloses them. PoC Self-contained reproducer:…

Published by the source

28 Jul 2026, 21:32 UTC

Last modified by the source

28 Jul 2026, 21:32 UTC

Source last checked

26 Oct 2026, 13:50 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-r5vv-ff45-prp2

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# Patch Next advisory brief: CVE-2026-55403

Advisory: datamodel-code-generator: Authorization / request headers leaked to cross-origin redirect target when fetching remote schemas
IDs: CVE-2026-55403, GHSA-r5vv-ff45-prp2
Record: https://patchnext.com/advisories/cve-2026-55403 (revision 1, source checked 26 Oct 2026, 13:50 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Low (CVSS 3.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: datamodel-code-generator 0.63.0. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI datamodel-code-generator: affected <= 0.62.0; fixed in 0.63.0

## Suggested inspection (read-only)
- `python -m pip show datamodel-code-generator`: 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 datamodel-code-generator.
- 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://github.com/advisories/GHSA-r5vv-ff45-prp2 (GitHub-reviewed advisory GHSA-r5vv-ff45-prp2 lists affected ranges: PyPI datamodel-code-generator >=0 <=0.62.0)

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