{"id":"CVE-2025-6921","summary":"Regular Expression Denial of Service (ReDoS) in huggingface/transformers","details":"The huggingface/transformers library, versions prior to 4.53.0, is vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer. The vulnerability arises from the _do_use_weight_decay method, which processes user-controlled regular expressions in the include_in_weight_decay and exclude_from_weight_decay lists. Malicious regular expressions can cause catastrophic backtracking during the re.search call, leading to 100% CPU utilization and a denial of service. This issue can be exploited by attackers who can control the patterns in these lists, potentially causing the machine learning task to hang and rendering services unresponsive.","aliases":["GHSA-4w7r-h757-3r74","PYSEC-2026-1980"],"modified":"2026-08-12T10:57:07.448241358Z","published":"2025-09-23T13:56:15.636Z","related":["CGA-m94h-gv3j-x4p3","openSUSE-SU-2026:11499-1"],"database_specific":{"cna_assigner":"@huntr_ai","cwe_ids":["CWE-400"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/6xxx/CVE-2025-6921.json"},"references":[{"type":"WEB","url":"https://huntr.com/bounties/287d15a7-6e7c-45d2-8c05-11e305776f1f"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/6xxx/CVE-2025-6921.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2025-6921"},{"type":"FIX","url":"https://github.com/huggingface/transformers/commit/47c34fba5c303576560cb29767efb452ff12b8be"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/huggingface/transformers","events":[{"introduced":"0"},{"fixed":"67ddc82fbc7e52c6f42a395b4a6d278c55b77a39"},{"fixed":"47c34fba5c303576560cb29767efb452ff12b8be"}],"database_specific":{"cpe":"cpe:2.3:a:huggingface:transformers:*:*:*:*:*:*:*:*","extracted_events":[{"introduced":"0"},{"fixed":"4.53.0"}],"source":["CPE_RANGE","REFERENCES"]}}],"versions":["v4.52.4-Kyutai-STT-preview","v4.52.4-VJEPA-2-preview","v4.52.4-ColQwen2-preview","v4.51.3-CSM-preview","v4.51.3-GraniteMoeHybrid-preview","v4.51.3-LlamaGuard-preview","v4.51.3-D-FINE-preview","v4.51.3-SAM-HQ-preview","v4.51.3-BitNet-preview","v4.51.3-InternVL-preview","v4.51.3-Janus-preview","v4.51.3-TimesFM-preview","v4.51.3-MLCD-preview","v4.51.3-Qwen2.5-Omni-preview","v4.50.3-DeepSeek-3","v4.49.0-Mistral-3","v4.49.0-AyaVision","v4.49.0-SigLIP-2","v4.49.0-SmolVLM-2","v4.33.1","v4.16.0","v4.15.0","v4.14.0","v4.13.0","v4.12.0","v4.11.0","v4.10.0","v4.9.0","v4.8.0","v4.7.0","v4.6.0","v4.5.0","v4.4.0","v4.3.0.rc1","4.3.0.rc1","v4.2.0","v4.1.1","v4.1.0","v3.5.0","v3.4.0","v3.3.1","v3.3.0","v3.2.0","v3.1.0","v3.0.2","v3.0.1","3.0.1","v3.0.0","v2.11.0","v2.10.0","v2.9.1","v2.9.0","v2.8.0","v2.7.0","v2.6.0","v2.5.1","v2.5.0","v2.4.1","v2.4.0","v2.3.0","v2.2.2","v2.2.1","v2.2.0","v2.1.1","v2.1.0","v2.0.0","1.2.0","1.1.0","1.0","v0.6.2","v0.6.1","v0.6.0","v0.5.1","v0.5.0","0.5.0","v0.4.0","v0.3.0","v0.2.0","v0.1.2","0.1.2"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-6921.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"}]}