webpack-dev-server up to 5.2.4 origin validation

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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5.2$0-$5k0.96

Summaryinfo

A vulnerability described as problematic has been identified in webpack-dev-server up to 5.2.4. This affects an unknown function. Such manipulation leads to origin validation. This vulnerability is listed as CVE-2026-9595. The attack may be performed from remote. There is no available exploit. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as problematic, has been found in webpack-dev-server up to 5.2.4. Affected by this issue is an unknown code block. The manipulation with an unknown input leads to a origin validation vulnerability. Using CWE to declare the problem leads to CWE-346. The product does not properly verify that the source of data or communication is valid. Impacted is availability. CVE summarizes:

Impact: When a user-configured proxy on webpack-dev-server has a broad context (e.g. /) and ws: true, it also intercepts the dev server's own HMR WebSocket and forwards it to the proxy target. This leaks the browser's cookies and Origin header to the backend, bypasses the dev server's Host/Origin validation, and corrupts the HMR socket (both HMR and the proxy end up writing to the same socket). Patches: Fixed in [email protected]. Workarounds: Scope user-defined proxy context to specific paths instead of /, or omit ws: true from the proxy entry when WebSocket forwarding is not required.

The weakness was presented by UlisesGascon as GHSA-mx8g-39q3-5c79. The advisory is shared for download at github.com. This vulnerability is handled as CVE-2026-9595 since 05/26/2026. The exploitation is known to be easy. The attack may be launched remotely. No form of authentication is required for exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 5.2.5 eliminates this vulnerability. Applying the patch 72ba7505aff2a8314e82aa5082379a77504a1fcb is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Name

Version

License

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.3
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.3
VulDB Temp Score: 5.1
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 5.3
CNA Vector (openjs): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Origin validation
CWE: CWE-346 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: webpack-dev-server 5.2.5
Patch: 72ba7505aff2a8314e82aa5082379a77504a1fcb

Timelineinfo

05/26/2026 CVE reserved
06/15/2026 +20 days Advisory disclosed
06/15/2026 +0 days VulDB entry created
06/15/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: GHSA-mx8g-39q3-5c79
Researcher: UlisesGascon
Status: Confirmed

CVE: CVE-2026-9595 (🔒)
GCVE (CVE): GCVE-0-2026-9595
GCVE (VulDB): GCVE-100-370928

Entryinfo

Created: 06/15/2026 18:32
Changes: 06/15/2026 18:32 (65)
Complete: 🔍
Cache ID: 216::103

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