CVE-2025-3264VulnerabilityPublished 7 Jul 2025

CVE-2025-3264: huggingface/transformers · ReDoS

Affects huggingface/transformersSource CVE Database V5

Not known to be exploited · CVSS 5.3 Medium : upgrade to 4.51.0 when convenient.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.0 base score

5.3Medium

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 42% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 4.51.0

CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 7 Jul 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 2026-10-25.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade transformers to 4.51.0.

Affected software

Product	Affected	Fixed in
PyPItransformers`pkg:pypi/transformers`Other threats	Affected >=4.49.0 <4.51.0	Fixed in 4.51.0

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should prioritize upgrading the Hugging Face Transformers library to version 4.51.0 or later, where the vulnerability is fixed. In environments where immediate upgrade is not feasible, organizations can implement input validation and sanitization to detect and block suspiciously complex or malformed inputs that could trigger the ReDoS condition. Monitoring CPU and memory usage patterns in AI model serving infrastructure can help detect anomalous resource consumption indicative of exploitation attempts. Incorporating rate limiting and request throttling mechanisms on endpoints that process user-supplied code or model inputs can reduce the risk of resource exhaustion. Additionally, organizations should review and harden their development pipelines to ensure that untrusted or external code is not processed without adequate scrutiny. Employing static analysis tools to detect inefficient regular expressions and potential ReDoS patterns in custom code can prevent similar vulnerabilities. Finally, maintaining an up-to-date inventory of AI/ML dependencies and integrating vulnerability scanning into CI/CD workflows will help promptly identify and remediate such issues.

Description

A Regular Expression Denial of Service (ReDoS) vulnerability was discovered in the Hugging Face Transformers library, specifically in the `get_imports()` function within `dynamic_module_utils.py`. This vulnerability affects versions 4.49.0 and is fixed in version 4.51.0. The issue arises from a regular expression pattern `\s*try\s*:.*?except.*?:` used to filter out try/except blocks from Python code, which can be exploited to cause excessive CPU consumption through crafted input strings due to catastrophic backtracking. This vulnerability can lead to remote code loading disruption, resource exhaustion in model serving, supply chain attack vectors, and development pipeline disruption.

Impact

For European organizations, the impact of this vulnerability can be significant, especially for those heavily invested in AI and machine learning workflows that utilize the Hugging Face Transformers library. Organizations providing AI model serving or inference as a service could face service disruptions due to resource exhaustion caused by maliciously crafted inputs exploiting this ReDoS vulnerability. This could lead to downtime, degraded performance, and potential cascading effects on dependent applications and services. Development teams relying on automated pipelines that incorporate the vulnerable library might experience delays or failures, impacting release cycles and operational efficiency. Additionally, supply chain risks arise if malicious actors exploit this vulnerability to disrupt or manipulate AI model deployment processes. While the vulnerability does not directly expose sensitive data or allow code execution, the availability impact could affect critical AI-driven services in sectors such as finance, healthcare, telecommunications, and public services across Europe. The medium severity rating suggests the threat is manageable but requires timely remediation to avoid operational risks.

CWE-1333Inefficient Regular Expression Complexity (opens in a new tab)
Base weaknessLikelihood of exploit: High
The product uses a regular expression with a worst-case computational complexity that is inefficient and possibly exponential.
Architecture and Design
Use regular expressions that do not support backtracking, e.g. by removing nested quantifiers.
System Configuration
Set backtracking limits in the configuration of the regular expression implementation, such as PHP's pcre.backtrack_limit. Also consider limits on execution time for the process.
Implementation
Do not use regular expressions with untrusted input. If regular expressions must be used, avoid using backtracking in the expression.
OWASP Cheat Sheets
File Upload (opens in a new tab)
OWASP ASVS 4.0.3
V12.1.1 (opens in a new tab)
Attack patterns
Regular Expression Exponential Blowup (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 7 Jul 2025, 10:26 UTC

WeaknessesCWE-1333

Technical details

References

Community reviews

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