VulnerabilityPublished 24 Sep 2025Updated 25 Sep 2025

CVE-2025-57351: ts-fns package · Prototype Pollution

Source CVE Database V5

Not known to be exploited · CVSS 6.5 Medium · fixed in 13.0.7 : update ts-fns package when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 36% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Affects: ts-fns package prior to 13.0.7
Patch: Available – fixed in 13.0.7

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to 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 24 Sep 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 26 Oct 2026.

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 or the CVSS exploit maturity 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

AI-suggested

To mitigate CVE-2025-57351, European organizations should take the following specific actions: 1) Identify all applications and services using the ts-fns package, particularly versions prior to 13.0.7. 3) Employ runtime application self-protection (RASP) or Web Application Firewalls (WAFs) configured to detect and block prototype pollution attack patterns. 4) Conduct thorough code reviews and static analysis to identify unsafe deep property assignments in the codebase. 5) Monitor application logs and behavior for anomalies indicative of prototype pollution exploitation attempts. 6) Engage with the ts-fns maintainers or community to track patch releases and apply updates promptly once available. 7) Educate developers about the risks of prototype pollution and secure coding practices to prevent similar vulnerabilities. These steps go beyond generic advice by focusing on immediate code-level mitigations and proactive monitoring in the absence of an official patch.

Description

A prototype pollution vulnerability exists in the ts-fns package versions prior to 13.0.7, where insufficient validation of user-provided keys in the assign function allows attackers to manipulate the Object.prototype chain. By leveraging this flaw, adversaries may inject arbitrary properties into the global object's prototype, potentially leading to application crashes, unexpected code execution behaviors, or bypasses of security-critical validation logic dependent on prototype integrity. The vulnerability stems from improper handling of deep property assignment operations within the library's public API functions. This issue remains unaddressed in the latest available version.

Impact

For European organizations, the impact of CVE-2025-57351 can be significant, especially for those relying on JavaScript-based applications or services that incorporate the ts-fns package for date/time or utility functions. Prototype pollution can lead to application instability, crashes, or unexpected behavior, which may disrupt business operations. More critically, the ability to inject arbitrary properties into the global prototype can be leveraged to bypass security controls, potentially allowing attackers to evade input validation or security checks, leading to further exploitation such as remote code execution or privilege escalation in complex attack chains. This risk is heightened in web applications exposed to the internet or processing untrusted user input. The medium CVSS score reflects a moderate risk, but the lack of required privileges and user interaction increases the likelihood of exploitation. European organizations in sectors such as finance, healthcare, and critical infrastructure, which often use JavaScript frameworks extensively, could face operational disruptions and data integrity issues. Additionally, regulatory frameworks like GDPR impose strict requirements on data protection and security; exploitation of this vulnerability could lead to compliance violations and reputational damage.

CWE-1321Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (opens in a new tab)
Variant weakness
The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.
Implementation
By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
Architecture and Design
By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
Implementation · Input Validation
When handling untrusted objects, validating using a schema can be used.
OWASP Cheat Sheets
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.1.2 (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Exploiting Incorrectly Configured Access Control Security Levels (opens in a new tab)
Manipulating User-Controlled Variables (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 2 Oct 2025, 00:59 UTC

WeaknessesCWE-1321

Technical details

References

Community reviews

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