CVE-2026-85670Public exploitNetwork attack vector

Process abort via merge buffer overrun

Published Sep 4, 2026 · Updated Sep 4, 2026

Out-of-bounds write in BpeBuilder in Hugging Face Tokenizers 0.23.2 and earlier allows attackers to abort a process via crafted tokenizer.json files. BpeBuilder::build sizes a scratch buffer to the longest vocabulary key, then copies each concatenated merge token without ensuring that it fits. Loading an attacker-supplied file through Tokenizer::from_file or from_str reaches the write before validation, causing a panic that can terminate Rust and FFI-hosted services.

CVSS severity7.1
High
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Out-of-bounds write in BpeBuilder in Hugging Face Tokenizers 0.23.2 and earlier allows attackers to abort a process via crafted tokenizer.json files. BpeBuilder::build sizes a scratch buffer to the longest vocabulary key, then copies each concatenated merge token without ensuring that it fits. Loading an attacker-supplied file through Tokenizer::from_file or from_str reaches the write before validation, causing a panic that can terminate Rust and FFI-hosted services.

The record

CVE
CVE-2026-85670
Published
Sep 4, 2026
Updated
Sep 4, 2026
Vendor
Hugging Face
Product
Tokenizers
Classifications
CWE-787, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 4, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 4, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=0.23.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hugging Face · Tokenizersversion=0 <=0.23.2

Published CVSS scores

6.5VulnCheck CNACVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H
7.1VulnCheck CNACVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-787Out-of-bounds Write
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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