VulnerabilityPublished 12 May 2026

CVE-2026-6402: webpack-dev-server · Exposed Dangerous Method or Function

Affects webpack-dev-serverSource GCVE Database

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Not known to be exploited · CVSS 5.3 Medium · fixed in 5.2.4 : update webpack-dev-server when convenient.

Data as of 11 Nov 2026, 23:18 UTC

CVSS 3.1 base score

5.3Medium

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

Thin evidence

One scorer or none

CVSS scores by source
CNA (openjs)	CVSS 3.1	5.3

Patch: Available – fixed in 5.2.4

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

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

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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
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: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 12 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 11 Nov 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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

Affected software

Product	Affected	Fixed in
webpack-dev-server webpack-dev-server	Affected =0 <=5.2.3	Fixed in–

AI-suggested

Upgrade webpack-dev-server to version 5.2.4 or later, which addresses the vulnerability by setting the Cross-Origin-Resource-Policy header to same-origin on responses. This fix prevents cross-origin source code exposure when serving over HTTP. No other mitigation is indicated.

Description

webpack-dev-server versions up to and including 5.2.3 have a vulnerability that allows cross-origin source code exposure when served over HTTP. This occurs because the previous mitigation relied on request headers that browsers omit for non-trustworthy origins, enabling a malicious site to read bundled source code across origins. Chromium-based browsers from Chrome 142 onward are not affected due to local network access restrictions. Upgrading to version 5.2.4 or later mitigates this issue by setting a strict Cross-Origin-Resource-Policy header.

Impact

An attacker who controls a website visited by a developer running a vulnerable version of webpack-dev-server over HTTP can recover the application's source code by exploiting cross-origin resource sharing weaknesses. This exposure compromises source code confidentiality but does not affect integrity or availability. Chromium-based browsers from Chrome 142 onward mitigate this risk via local network access restrictions.

CWE-749Exposed Dangerous Method or Function (opens in a new tab)
Base weaknessLikelihood of exploit: LowOWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The product provides an Applications Programming Interface (API) or similar interface for interaction with external actors, but the interface includes a dangerous method or function that is not properly restricted.
Architecture and Design
If you must expose a method, make sure to perform input validation on all arguments, limit access to authorized parties, and protect against all possible vulnerabilities.
Architecture and Design · Implementation · Attack Surface Reduction
Identify all exposed functionality. Explicitly list all functionality that must be exposed to some user or set of users. Identify which functionality may be: accessible to all users; restricted to a small set of privileged users; prevented from being directly accessible at all
OWASP Cheat Sheets
Third Party Javascript Management (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V14.5.1 (opens in a new tab)
V10.1.1 (opens in a new tab)
V1.4.4 (opens in a new tab)
Attack patterns
WebView Injection (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

Affected software

Description

AI analysisMachine-generated, updated 11 Nov 2026, 23:18 UTC

WeaknessesCWE-749

Technical details

References

Community reviews

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