VulnerabilityPublished 26 Jan 2026

CVE-2025-50537: eslint · Stack Overflow

Affects eslintSource CVE Database V5

Not known to be exploited · CVSS 5.5 Medium : upgrade to 9.26.0 when convenient.

Data as of 26 Oct 2026, 12:55 UTC

CVSS 3.1 base score

5.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 9% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 9.26.0

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

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

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

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Jan 2026
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

Upgrade eslint to 9.26.0.

Affected software

Product	Affected	Fixed in
npmeslint`pkg:npm/eslint`Other threats	Affected <9.26.0	Fixed in 9.26.0

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

AI-suggested

To mitigate CVE-2025-50537, European organizations should: 1) Upgrade eslint to version 9.26.0 or later, where the serialization issue has been addressed. 2) Audit existing test cases used with RuleTester to identify and refactor or remove any that include circular references, preventing infinite recursion during serialization. 3) Integrate static analysis or linting checks in CI/CD pipelines to detect usage of vulnerable eslint versions and prevent deployment of problematic test cases. 4) Educate development teams about the risks of circular references in test objects and encourage best practices in test case design. 6) If upgrading immediately is not feasible, consider isolating eslint runs in containerized or sandboxed environments to limit the impact of potential crashes. 7) Implement robust error handling in build scripts to gracefully manage eslint failures and avoid cascading pipeline disruptions.

Description

Stack overflow vulnerability in eslint before 9.26.0 when serializing objects with circular references in eslint/lib/shared/serialization.js. The exploit is triggered via the RuleTester.run() method, which validates test cases and checks for duplicates. During validation, the internal function checkDuplicateTestCase() is called, which in turn uses the isSerializable() function for serialization checks. When a circular reference object is passed in, isSerializable() enters infinite recursion, ultimately causing a stack overflow.

Impact

For European organizations, the primary impact of CVE-2025-50537 is disruption of software development and testing processes. Since eslint is a popular tool in JavaScript development, organizations relying on it for code quality assurance may experience crashes or failures in their linting and testing pipelines if vulnerable versions are used with test cases containing circular references. This can delay development cycles, reduce developer productivity, and increase the risk of shipping code without proper linting validation. Although the vulnerability does not directly compromise confidentiality or integrity, denial of service in build environments can have downstream effects on release schedules and operational stability. Organizations with automated CI/CD pipelines that incorporate eslint RuleTester are particularly at risk. The absence of known exploits reduces immediate threat but does not eliminate the risk of targeted attacks or accidental disruptions. European companies in sectors with heavy software development, such as finance, telecommunications, and technology, may face operational impacts if mitigation is not applied promptly.

CWE-674Uncontrolled Recursion (opens in a new tab)
Class weakness
The product does not properly control the amount of recursion that takes place, consuming excessive resources, such as allocated memory or the program stack.
Implementation
Ensure that an end condition will be reached under all logic conditions. The end condition may include checking against the depth of recursion and exiting with an error if the recursion goes too deep. The complexity of the end condition contributes to the effectiveness of this action.
Implementation
Increase the stack size.
Attack patterns
Serialized Data with Nested Payloads (opens in a new tab)
Oversized Serialized Data Payloads (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 26 Jan 2026, 16:05 UTC

WeaknessesCWE-674

Technical details

References

Community reviews

Related threats