{"id":"CVE-2026-85670","title":"tokenizers (Hugging Face) is affected by an out-of-bounds buffer access in BpeBuilder::build (tokenizers/src/models/bpe/model.rs)","summary":"tokenizers (Hugging Face) is affected by an out-of-bounds buffer access in BpeBuilder::build (tokenizers/src/models/bpe/model.rs). When loading a tokenizer.json via Tokenizer::from_file/from_str, the builder sizes a scratch buffer to the…","severity":"medium","cvss":6.5,"cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H","cwe":["CWE-787"],"published":"2026-09-04","updated":"2026-09-24","sourceUpdated":"2026-09-24T20:28:01.780","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-85670","references":[{"url":"https://github.com/huggingface/tokenizers","label":"disclosure@vulncheck.com"},{"url":"https://github.com/huggingface/tokenizers/blob/v0.23.2/tokenizers/src/models/bpe/model.rs","label":"disclosure@vulncheck.com"},{"url":"https://github.com/huggingface/tokenizers/issues/2094","label":"disclosure@vulncheck.com"},{"url":"https://www.vulncheck.com/advisories/tokenizers-bpebuilder-buffer-overflow-via-merge-token","label":"disclosure@vulncheck.com"},{"url":"https://github.com/huggingface/tokenizers/issues/2094","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd"],"epss":0.00467,"epssPercentile":0.37742,"ingestedAt":"2026-09-24T20:51:40.243Z","slug":"CVE-2026-85670","body":"## Overview\n\ntokenizers (Hugging Face) is affected by an out-of-bounds buffer access in BpeBuilder::build (tokenizers/src/models/bpe/model.rs). When loading a tokenizer.json via Tokenizer::from_file/from_str, the builder sizes a scratch buffer to the longest vocabulary key, then writes each concatenated merge rule into it. A merge whose concatenated token exceeds the longest vocabulary key overruns the buffer, which Rust turns into a panic that aborts the process in Rust and FFI embeddings. This occurs at load time with no encoding required, so an attacker who supplies a crafted tokenizer.json can cause a denial of service. A secondary defect at the same location can cause a usize underflow (panic in debug, potential memory corruption in release) when continuing_subword_prefix is set and a merge token is shorter than the prefix. Observed in version 0.23.1.\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":36,"depthScoreParts":{"impact":35.8,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}