Vulnerability · Published Nov 3, 2026 · Assigned by GitHub_M
CVE-2026-115878Stanza: RCE via pickle deserialization in the lemmatizer
High 7.8
In plain English
A high-severity code injection in stanza from stanfordnlp. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 49% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| PyPI | stanza | 1.15.0 | GHSA-gh9r-c94j-cmp5 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| stanfordnlp | stanza | = 1.14.0 |
Weakness: CWE-94, CWE-502 · Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
References
- https://github.com/stanfordnlp/stanza/security/advisories/GHSA-gh9r-c94j-cmp5 x_refsource_CONFIRM
- https://github.com/stanfordnlp/stanza/pull/1649 x_refsource_MISC
- https://github.com/stanfordnlp/stanza/commit/b21e1c9b47b4fccff21d3b0a6c0687a19410c2f0 x_refsource_MISC
- https://github.com/stanfordnlp/stanza/releases/tag/v1.15.0 x_refsource_MISC