CVE-2025-3262Network attack vector

Chat processing hang via exponential regex backtracking

Published Jul 7, 2025 · Updated Jul 7, 2025

Regular expression denial of service in Hugging Face Transformers 4.49.0 through 4.50.3 allows remote attackers to hang chat processing. SETTING_RE in transformers/commands/chat.py applies a nested, backtracking expression to almost-matching setting commands instead of bounded parsing. Exposure requires attacker-controlled input to reach the interactive chat command's setting parser; the bounded impact is excessive CPU use and a hang.

CVSS severity5.3
Medium
EPSS probability0.43%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Regular expression denial of service in Hugging Face Transformers 4.49.0 through 4.50.3 allows remote attackers to hang chat processing. SETTING_RE in transformers/commands/chat.py applies a nested, backtracking expression to almost-matching setting commands instead of bounded parsing. Exposure requires attacker-controlled input to reach the interactive chat command's setting parser; the bounded impact is excessive CPU use and a hang.

The record

CVE
CVE-2025-3262
Published
Jul 7, 2025
Updated
Jul 7, 2025
Vendor
Hugging Face
Product
Hugging Face Transformers
Classifications
CWE-1333, CAPEC-492, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 7, 2025CVE publishedPublication date reported by the CVE source.
  2. Jul 7, 2025Record 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=unspecified <4.51.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Hugging Face · Hugging Face Transformersversion=unspecified <4.51.0

Published CVSS scores

5.3GitHub Advisory DatabaseCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-1333Inefficient Regular Expression Complexity
CAPEC-492Regular Expression Exponential Blowup
T1499.004Endpoint Denial of Service: Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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