Service interruption via catastrophic numeric-regex backtracking
Published Sep 14, 2025 · Updated Sep 14, 2025
Regular expression denial of service in Hugging Face Transformers before 4.53.0 allows remote attackers to interrupt services via numeric input. EnglishNormalizer.normalize_numbers applies backtracking-prone digit and currency substitutions to attacker-controlled text, and long digit sequences force excessive regex work. Exploitation requires a consuming application to pass remote input into CLVP English number normalization; the bounded result is CPU exhaustion and a service hang.
Summary
What happened
Regular expression denial of service in Hugging Face Transformers before 4.53.0 allows remote attackers to interrupt services via numeric input. EnglishNormalizer.normalize_numbers applies backtracking-prone digit and currency substitutions to attacker-controlled text, and long digit sequences force excessive regex work. Exploitation requires a consuming application to pass remote input into CLVP English number normalization; the bounded result is CPU exhaustion and a service hang.
The record
- CVE
- CVE-2025-6051
- Published
- Sep 14, 2025
- Updated
- Sep 14, 2025
- Vendor
- Hugging Face
- Product
- Hugging Face Transformers
- Classifications
- CWE-1333, T1499
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 14, 2025CVE publishedPublication date reported by the CVE source.
- Sep 14, 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.
- Affected versionversion=unspecified <4.53.0
What conditions does exploitation require?
What is affected?
Published CVSS scores
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.
Weakness, pattern, technique
Public exploit references
- EnglishNormalizer long-digit ReDoS proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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