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Full vulnerability report · 2025
CVE-2025-6638High confidence

Regular Expression Denial of Service (ReDoS) in huggingface/transformers

huggingface · huggingface/transformers

7.5HighCVSS 3.1
Recommended action
Within 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityHighOperational priority:Critical, raised one band.upgradedsince 12 Sep 2025

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.53% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs huggingface huggingface/transformers and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Open-source package ranges2 source-attributed ranges

These OSV and GitHub advisory ranges apply only to the named package and ecosystem. A listed fixed version is not a universal product patch or proof that an update is installed.

Ecosystem and packageAffected rangeFirst fixed versionEvidence
PyPItransformersECOSYSTEM: introduced 0; fixed 4.53.04.53.0OSV record ↗aggregator derived · 10 Sep 2026
piptransformers< 4.53.04.53.0GitHub advisory ↗github reviewed aggregator · 15 Sep 2025
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2025-29032

No EUVD known-exploited evidence

ENISA has published the identifier mapping but no EUVD description has been stored yet.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
Not supplied in the stored EUVD record
Advisory evidence
No linked advisory details stored yet
Recommended actionWithin 7 days

High technical severity with public exploit material referenced by a structured source; prioritise exposed affected systems while verifying vendor guidance.

Patch available
01

What, why and how

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

What

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

Why

The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

What

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

Why

The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

A structured CVE source labels at least one public reference as exploit material. BlackTree has not independently validated that it is safe, reliable or weaponised.

Likely attack path
a network path → Inefficient Regular Expression Complexity → disrupt the affected service
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Unchanged: impact remains within the vulnerable component's security authority
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-1333 ↗

CWE-1333: Inefficient Regular Expression Complexity. The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Common Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.
Post-exploitation / living off the land
Stolen credentials, tokens and legitimate administration functions may provide continued access without deploying a large custom toolset.
NetworkUnauthenticatedDenial of serviceCWE-1333Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

Cyber Security Agency of Singapore · English · CSA-SB-20250917SECURITY BULLETIN 17 SEPT 2025

The Cyber Security Agency of Singapore included this CVE in its official SECURITY BULLETIN 17 SEPT 2025, published on 17 September 2025. Open the linked bulletin for the product, severity and reference information published in that issue.

Official advisory ↗
CERT-FR · French · CERTFR-2026-AVI-0556Multiples vulnérabilités dans les produits VMware

d?id=CVE-2025-61727 Référence CVE CVE-2025-61728 https://www.cve.org/CVERecord?id=CVE-2025-61728 Référence CVE CVE-2025-61729 https://www.cve.org/CVERecord?id=CVE-2025-61729 Référence CVE CVE-2025-61730 https://www.cve.org/CVERecord?id=CVE-2025-61730 Référence CVE CVE-2025-61731 https://www.cve.org/CVERecord?id=CVE-2025-61731 Référence CVE CVE-2025-61732 https://www.cve.org/CVERecord?id=CVE-2025-61732 Référence CVE CVE-2025-62813 https://www.cve.org/CVERecord?id=CVE-2025-62813 Référence CVE CVE-2025-66034 https://www.cve.org/CVERecord?id=CVE-2025-66034 Référence CVE CVE-2025-66221 https://www.cve.org/CVERecord?id=CVE-2025-66221 Référence CVE CVE-2025-6638 https://www.cve.org/CVERecord?id=CVE-2025-6638 Référence CVE CVE-2025-66418 https://www.cve.org/CVERecord?id=CVE-2025-66418 Référence CVE CVE-2025-66471 https://www.cve.org/CVERecord?id=CVE-2025-66471 Référence CVE CVE-2025-66516 https://www.cve.org/CVERecord?id=CVE-2025-66516 Référence CVE CVE-2025-66614 https://www.cve.org/CVERecord?id=CVE-2025-66614 Référence CVE CVE-2025-67221 https://www.cve.org/CVERecord?id=CVE-2025-67221 Référence CVE CVE-2025-68121 https://www.cve.org/CVERecord?id=CVE-2025-68121 Référence CVE CVE-2025-68146 https://www.cve.org/CVERecord?id=CVE-2025-68146 Référence CVE CVE-2025-68161 https://www.cve.org/CVERecord?id=C

Official advisory ↗
CERT-FR · French · CERTFR-2025-AVI-0969Multiples vulnérabilités dans les produits VMware

ecord?id=CVE-2025-61795 Référence CVE CVE-2025-61919 https://www.cve.org/CVERecord?id=CVE-2025-61919 Référence CVE CVE-2025-61921 https://www.cve.org/CVERecord?id=CVE-2025-61921 Référence CVE CVE-2025-61984 https://www.cve.org/CVERecord?id=CVE-2025-61984 Référence CVE CVE-2025-61985 https://www.cve.org/CVERecord?id=CVE-2025-61985 Référence CVE CVE-2025-62171 https://www.cve.org/CVERecord?id=CVE-2025-62171 Référence CVE CVE-2025-62813 https://www.cve.org/CVERecord?id=CVE-2025-62813 Référence CVE CVE-2025-6297 https://www.cve.org/CVERecord?id=CVE-2025-6297 Référence CVE CVE-2025-6395 https://www.cve.org/CVERecord?id=CVE-2025-6395 Référence CVE CVE-2025-6638 https://www.cve.org/CVERecord?id=CVE-2025-6638 Référence CVE CVE-2025-6921 https://www.cve.org/CVERecord?id=CVE-2025-6921 Référence CVE CVE-2025-6965 https://www.cve.org/CVERecord?id=CVE-2025-6965 Référence CVE CVE-2025-7039 https://www.cve.org/CVERecord?id=CVE-2025-7039 Référence CVE CVE-2025-7424 https://www.cve.org/CVERecord?id=CVE-2025-7424 Référence CVE CVE-2025-7425 https://www.cve.org/CVERecord?id=CVE-2025-7425 Référence CVE CVE-2025-7709 https://www.cve.org/CVERecord?id=CVE-2025-7709 Référence CVE CVE-2025-7783 https://www.cve.org/CVERecord?id=CVE-2025-7783 Référence CVE CVE-2025-7962 https://www.cve.org/CVERecord?id=CVE-2025-7962 Ré

Official advisory ↗
JVN iPedia · Japanese · JVNDB-2025-016958huggingface の transformers における非効率的な正規表現の複雑さに関する脆弱性

huggingface の transformers には、非効率的な正規表現の複雑さに関する脆弱性が存在します。

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Patch available
Affected
huggingface/transformers: unspecified < 4.53.0
Fixed
4.53.0.
Action
Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
Workaround
No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04

Evidence and provenance

Published 12 Sept 2025 · Last source change 12 Sept 2025, 11:52 UTC · CWE-1333 · Inefficient Regular Expression Complexity

CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-08-14
European sourceENISA EUVD · EUVD-2025-29032
Product sourceCNA
Remediation sourceCVE/CNA references
CWE sourceCNA
NVD statusNVD enriched

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗

No material field changes have been recorded since change tracking began. Routine source refreshes and cosmetic edits are intentionally excluded.

Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
CVE published
Fixed release or patch reference recorded
ENISA EUVD · EUVD-2025-29032↗CISA Vulnrichment SSVC evidence↗Patch or update reference↗Public exploit reference↗Official CVE record (CNA and ADP data)↗NVD record↗
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2025-6638 · cve.blacktree.nl