CVE-2025-30359: webpack-dev-server users' source code may be stolen when they access a malicious web site
Noroxi assessment
Priority: Monitor (action score 23/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 0.59% (FIRST EPSS).
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. Special conditions such as timing or configuration are required.
- Fixed version: webpack-dev-server (npm) 5.2.1.
Low priority for now. Upgrade to webpack-dev-server (npm) 5.2.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
webpack-dev-server allows users to use webpack with a development server that provides live reloading. Prior to version 5.2.1, webpack-dev-server users' source code may be stolen when they access a malicious web site. Because the request for classic script by a script tag is not subject to same origin policy, an attacker can inject a malicious script in their site and run the script. Note that the attacker has to know the port and the output entrypoint script path. Combined with prototype pollution, the attacker can get a reference to the webpack runtime variables. By using `Function::toString` against the values in `__webpack_modules__`, the attacker can get the source code. Version 5.2.1 contains a patch for the issue.
- Published
- Jun 3, 2025
- Updated
- Jun 17, 2026
- EPSS
- 0.5% · 48th percentile
- CWE
- CWE-749
Report tools
Action score
23
Monitor
Low priority for now.
- CVSS
- 23 / 40 · 5.9 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 0 / 30 · 0.5%
CISA SSVC decision
- Exploitation
- proof of concept
- Automatable
- no
- Technical impact
- partial
Vulnrichment: CISA's decision-tree inputs.
CNA vs NVD score
- NVD
- 5.9
- CNA · GitHub_M
- 5.3
- 0.6 point gap
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:N/A:N
The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| webpack.js | webpack-dev-server | cpe:2.3:a:webpack.js:webpack-dev-server |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- webpack.js webpack-dev-serverbefore 5.2.1
Versions reported by the vendor
Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.
webpack webpack-dev-server
- < 5.2.1affected
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| npm | webpack-dev-server | before 5.2.1 | 5.2.1 |
Same product
webpack.js: all recordsOther highest-scoring records for the same primary product.
- CVE-2026-112085webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades32Monitor
- CVE-2018-14732An issue was discovered in lib/Server.js in webpack-dev-server before 3.1.6.31Monitor
- CVE-2026-6402webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins26Monitor
Published before and after this one in the same product
- Later →CVE-2025-30360Jun 3, 2025 · webpack-dev-server users' source code may be stolen when they access a malicious web site with non-Chromium based browser26Monitor
- Later →CVE-2026-9595Jun 15, 2026 · webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies17Monitor
- Later →CVE-2026-14620Jul 3, 2026 · webpack-dev-server vulnerable to cross-site request forgery via internal developer endpoints18Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| npm:webpack-dev-server | 5.2.1 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
- CVE-2026-6402343 days apartwebpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins26Monitor
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- Special conditions such as timing or configuration are required.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- High
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-749 · Exposed Dangerous Method or FunctionCVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
nvd-primary
Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
ATT&CK techniques
—
Change log
- Fix✗ → ✓
For records you follow, these changes also arrive as notifications. →
References
Vendor advisories and official records. Exploit/PoC links are deliberately left out.