CVE-2026-85670

7.1 HIGH 0.5% exploit odds No fix listed Memory safety

What it is

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 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.

At a glance

Exploitability: Can be exploited over the network without logging in, but needs a user to act. High risk of service disruption.
Exploit odds: 0.5% chance of exploitation in the next 30 days (EPSS).
Fix: No patch or advisory is linked yet. Look at mitigations or restrict exposure.

Timeline

2026-09-04 13:32 UTC ReservedThe CVE id was reserved by its CNA
2026-09-04 15:17 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-09-24 20:28 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.5% in the next 30 days (EPSS).
Severity: 7.1 HIGH (CVSS).
Fix: none linked yet, which raises it.

Details

Published: 2026-09-04 15:17 UTC
Last modified: 2026-09-24 20:28 UTC
Exploit probability: 0.5% · EPSS, next 30 days
Weakness: CWE-787 · Out-of-bounds write
Record status: Awaiting Analysis

Attack profile CVSS 4.0 · 7.1

Attack vector: Network
Complexity: Low
Attack requirements: None
Privileges needed: None
User interaction: Passive
Confidentiality: None
Integrity: None
Availability: High

Raw vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

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References

NVD record · CVE.org record