# CVE-2026-115878: Stanza: RCE via pickle deserialization in the lemmatizer

Status: published. Published: 2026-11-03. Updated: 2026-11-03.

Stanza is a Stanford NLP Python library for tokenization, sentence segmentation, NER, and parsing of many human languages. From 1.14.0 until 1.15.0, loading an attacker-supplied lemmatizer checkpoint can execute arbitrary code because stanza/models/lemma/trainer.py stores pos_dict as gzip-compressed pickle bytes and Trainer.load passes the decompressed stream to unrestricted pickle.loads. The outer torch.load call uses weights_only=True, but the nested bytes are treated as a primitive and are not inspected by that allowlist. The path is reachable during pipeline construction through a caller-influenced lemma_model_path, before inference begins. This issue is fixed in version 1.15.0.

## Remediation

- fix: stanza (PyPI): OSV reports a fixed version 1.15.0. Check the advisory for supported release branches. (source: OSV GHSA-gh9r-c94j-cmp5) — https://github.com/advisories/GHSA-gh9r-c94j-cmp5

## Affected products and versions

- stanfordnlp / stanza: = 1.14.0 (affected). Source: CNA: GitHub_M
-  / stanza (stanza): 1.14.0 (affected, PyPI); Ecosystem version events: introduced 1.14.0; fixed 1.15.0. Source: OSV GHSA-gh9r-c94j-cmp5

## Severity and prioritization

- CVSS 3.1: 7.8 (high); CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H; source: CNA: GitHub_M

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: exploitation none; automatable no; technical impact total; source ADP: CISA-ADP

- Weaknesses: CWE-94, CWE-502

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/stanfordnlp/stanza/security/advisories/GHSA-gh9r-c94j-cmp5 (CNA: GitHub_M; x_refsource_CONFIRM)

- https://github.com/stanfordnlp/stanza/pull/1649 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/stanfordnlp/stanza/commit/b21e1c9b47b4fccff21d3b0a6c0687a19410c2f0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/stanfordnlp/stanza/releases/tag/v1.15.0 (CNA: GitHub_M; x_refsource_MISC)

- https://github.com/advisories/GHSA-gh9r-c94j-cmp5 (OSV / GitHub Security Advisories; advisory)

- https://osv.dev/vulnerability/GHSA-gh9r-c94j-cmp5 (OSV / GitHub Security Advisories; osv)

## Provenance

- CNA: GitHub_M: https://www.cve.org/CVERecord?id=CVE-2026-115878; retrieved 2026-11-03; source updated 2026-11-03

- OSV / GitHub Security Advisories: https://osv.dev/vulnerability/GHSA-gh9r-c94j-cmp5; retrieved 2026-11-03; source updated 2026-11-03

Revision: adb906a46abbabc37f23435171261efddb65ea0b2b4170eddb84b41ac71f4165

Canonical: https://y2.dev/cve/CVE-2026-115878

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