TI-2025-06294 Aliases CVE-2025-6921 GHSA-4w7r-h757-3r74

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

HIGH 72CWE-400Published 2025-09-23 · Updated 2025-09-23

Key facts

Attack vector: Network
Privileges required: None
User interaction: None
Attack complexity: Low
Impact type: Denial of service
Confidentiality · integrity · availability: None · None · High
Fix status: Partial Red Hat: 5 without a fix

Attack profile from CVSS 3.1 · NVD. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

The huggingface/transformers library, versions prior to 4.53.0, is vulnerable to Regular Expression Denial of Service (ReDoS) in the AdamWeightDecay optimizer. The vulnerability arises from the _do_use_weight_decay method, which processes user-controlled regular expressions in the include_in_weight_decay and exclude_from_weight_decay lists. Malicious regular expressions can cause catastrophic backtracking during the re.search call, leading to 100% CPU utilization and a denial of service. This issue can be exploited by attackers who can control the patterns in these lists, potentially causing the machine learning task to hang and rendering services unresponsive.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV

EPSS 0.00511 43rd percentileScored 2026-11-07

Public exploit Yes 1 exploit referenceTagged by NVD

Fix Partial huggingface/transformers (huggingface): 4.53.0transformers (PyPI): 4.53.0Red Hat: 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation: Poc
Automatable: Yes
Technical impact: Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

Vendor	Product	Affected versions	Fixed in	Status	Source
huggingface	huggingface/transformers	before 4.53.0	4.53.0	Patch available	CNA
—	transformers (PyPI)	before 4.53.0	4.53.0	Patch available	GHSA-4w7r-h757-3r74

huggingface/transformers Vendorhuggingface Affected before 4.53.0 Fixed in 4.53.0 Patch available CNA
transformers (PyPI) Vendor— Affected before 4.53.0 Fixed in 4.53.0 Patch available GHSA-4w7r-h757-3r74

CPE configurations NVD · 1

CPE	Versions	Role	Vendor
cpe:2.3:a:huggingface:transformers::::::::	before 4.53.0	Vulnerable	huggingface

cpe:2.3:a:huggingface:transformers:*:*:*:*:*:*:*:* Versions before 4.53.0 Vulnerable ·huggingface

Remediation

Fix · CNA huggingface/transformers (huggingface) Fixed in 4.53.0
Fix · GHSA-4w7r-h757-3r74 transformers (PyPI) Fixed in 4.53.0 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

Product	Status	Plan or fix
OpenShift Lightspeed	Affected	No fix yet: Fix deferred
Red Hat AI Inference Server	Affected	No fix yet: Fix deferred
Red Hat Ansible Automation Platform 2	Affected	No fix yet: Fix deferred
Red Hat Enterprise Linux AI (RHEL AI)	Affected	No fix yet: Fix deferred
Red Hat OpenShift AI (RHOAI)	Affected	No fix yet: Fix deferred

Timeline

2026-10-02 Threatist record created from CVE-2025-6921
2026-10-03 Alias added: GHSA-4w7r-h757-3r74

References

Other 2

TI-2026-04577 Policy Bypass in LightGlue Nested Config Resolution in huggingface/transformers CVSS 3.1CRITICAL 9.6
TI-2025-06027 Regular Expression Denial of Service (ReDoS) in huggingface/transformers CVSS 3.1HIGH 7.5
TI-2025-02858 Regular Expression Denial of Service (ReDoS) in huggingface/transformers CVSS 3.1HIGH 7.5
TI-2025-01837 Regular Expression Denial of Service (ReDoS) in huggingface/transformers CVSS 3.1HIGH 7.5
TI-2024-11793 Regular Expression Denial of Service (ReDoS) in huggingface/transformers CVSS 3.1HIGH 7.5
TI-2026-01514 Arbitrary Code Execution via Unsafe torch.load() in Trainer Checkpoint Loading in huggingface/transformers CVSS 3.1HIGH 7.8

See all 29 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences