Stanza: Remote Code Execution via Unsafe Pickle Deserialization in Model Loaders

Exploitation

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

CVSS

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

EPSS

• CVE-2026-54499: 0.52% estimated exploitation activity in the next 30 days; percentile 44.14 (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 Stanza 1.12.0 attempts to safely load PyTorch checkpoint files using torch.load(..., weightsonly=True), but automatically falls back to the fully unsafe torch.load(..., weightsonly=False) when the safe load raises pickle.UnpicklingError. Because the UnpicklingError condition is fully attacker-controllable, any .pt file that contains a single unsupported pickle global will trigger it. An attacker who can place a malicious pretrain or model file on disk (via supply-chain compromise, a poisoned model repository, or a shared model cache) can achieve arbitrary code execution on any machine that loads a Stanza NLP pipeline. Code execution occurs inside the Stanza pretrain-loading API, not merely by calling torch.load directly. Details The vulnerable code is in pretrain.py#L59-L67 (Stanza 1.12.0): When weightsonly=True is passed, PyTorch's deserializer raises pickle.UnpicklingError for any object whose class or callable is not on the safe-globals allowlist. This is the intended…

Published by the source

19 Jun 2026, 19:35 UTC

Last modified by the source

13 Jul 2026, 16:43 UTC

Source last checked

26 Oct 2026, 13:46 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-v5jw-96jm-7h2c

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-v5jw-96jm-7h2c

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# Patch Next advisory brief: CVE-2026-54499

Advisory: Stanza: Remote Code Execution via Unsafe Pickle Deserialization in Model Loaders
IDs: CVE-2026-54499, GHSA-v5jw-96jm-7h2c
Record: https://patchnext.com/advisories/cve-2026-54499 (revision 2, source checked 26 Oct 2026, 13:46 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: stanza 1.12.2. A vendor fix does not mean a deployment is fixed.

## Affected components
- PyPI stanza: affected <= 1.12.1; fixed in 1.12.2

## Suggested inspection (read-only)
- `python -m pip show stanza`: 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 stanza.
- 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-v5jw-96jm-7h2c (OSV record GHSA-v5jw-96jm-7h2c lists affected ranges: PyPI stanza >=0 <1.12.2 (fixed))
- Verified: https://github.com/advisories/GHSA-v5jw-96jm-7h2c (GitHub-reviewed advisory GHSA-v5jw-96jm-7h2c lists affected ranges: PyPI stanza >=0 <=1.12.1)

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