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Vulnerabilities

Vulnerability · CVE-2025-6638

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's method.

Published Sep 12, 2025 · catalog updated Sep 12, 2025 · A Regular Expression Denial

Last checked Oct 28, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2025-6638. EPSS is 0.56%. Act only if a listed version of A Regular Expression Denial is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (A Regular Expression Denial).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Medium5.3
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.56%
Remediation
Version ranges on file
Affected products
vendor huggingface huggingface/transformers unspecified <4.53.0

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0. The issue arises from inefficient regex processing, which can be exploited by crafted input strings containing malformed language code patterns, leading to excessive CPU consumption and potential denial of service.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor huggingface huggingface/transformers unspecified <4.53.0unspecified <4.53.0

How to fix CVE-2025-6638

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-6638. EPSS is 0.56%. Act only if a listed version of A Regular Expression Denial is installed.

Which versions are affected?

Compare what you have installed with huggingface huggingface/transformers unspecified <4.53.0 unspecified <4.53.0. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.56%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 12, 2025 · EUVD

    Detected

    A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0. The issue arises from inefficient regex processing, which can be exploited by crafted input strings containing malformed language code patterns

  2. Sep 12, 2025 · EUVD

    Updated

    A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0. The issue arises from inefficient regex processing, which can be exploited by crafted input strings containing malformed language code patterns

Sources

  • CVE.orgVulnerability recordCVE-2025-6638

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-6638

    30-day exploitation probability 0.56%

    first.org
  • EUVDVulnerability recordEUVD-2025-29032

    A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically affecting the MarianTokenizer's method. This vulnerability is present in version 4.52.4 and has been fixed in version 4.53.0. The issue arises from i

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 28, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • FIRST EPSSOct 28, 2026
  • CVE.orgOct 22, 2026
  • EUVDOct 22, 2026