Medium Info disclosure

CVE-2026-114348 — webpack-dev-server vulnerable to information disclosure via Host validation bypass in the open-editor endpoint

webpack-dev-server is a development server that provides live reloading for webpack projects. In versions from 5.1.0 before 5.2.7 and in version 6.0.0, the unauthenticated open-editor endpoint validates the Host header with a regular expression meant for browser Origin schemes, so a Host value beginning with file: or with an extension scheme short-circuits the hostname and allowedHosts checks. A network peer that can reach the dev server can send a request with a malformed Host that passes validation and then causes the endpoint's URL construction to throw, and in the default non-production mode the server returns an HTTP 500 body containing the full exception stack trace, which discloses absolute filesystem paths, installed module locations, and internal source line numbers. The server keeps running, so there is no denial of service. The issue is fixed in webpack-dev-server 5.2.7 and 6.1.0, and users should upgrade to one of those versions or later.

Published Oct 22, 2026 · Updated Oct 22, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: openjs

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.3% (30-day exploitation probability)+3
Technical severity (medium)+3
Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.31%

ahead of 22% of scored CVEs · Oct 23, 2026

Affects

Webpack-dev-server

CVSS base

5.3

Medium · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

Yes

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Webpack-dev-server Webpack-dev-server).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (info disclosure), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Webpack-dev-server	Webpack-dev-server	≥ 5.1.0 and < 5.2.7≥ 6.0.0 and < 6.1.0	Vulnerable	CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
5.3	CVSS 3.1	Medium	3.9	1.4	ce714d77-add3-4f53-aff5-83d477b104bb via NIST National Vulnerability Database
5.3	CVSS 3.1	Medium	—	—	openjs via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N (score shown at the top: ce714d77-add3-4f53-aff5-83d477b104bb)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-209 · Information Exposure Through an Error Message

Other CVEs with this weakness →

EPSS over time FIRST

Oct 22, 2026 → Oct 23, 2026 · 2 reading(s) · max 0.34%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Look for anomalous data read/export volumes and access to sensitive records.

web/proxy/WAF logsnetwork IDS/IPSapplication logsauthentication logs

Timeline

What happened to this CVE, newest first.

2026
Source status changed · Received → Undergoing Analysis
Oct 22, 2026 · NIST National Vulnerability Database
SSVC assessment updated
Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
Affected products added · webpack-dev-server/webpack-dev-server
Oct 22, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 22, 2026
CVSS changed · 5.3
Oct 22, 2026 · NIST National Vulnerability Database
Source status changed · → Received
Oct 22, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 22, 2026 · Alertas do Telegram
CVE published
Oct 22, 2026 · openjs

Source activity

Repeated readings are counted rather than listed.

1× References added · Oct 22, 2026 – Oct 22, 2026
1× Official description updated · Oct 22, 2026 – Oct 22, 2026

References

2 on the record

github.com/webpack/webpack-dev-server/security/advisories/GHSA-wqhc-fvfg-56q6
NIST National Vulnerability Database
cna.openjsf.org/security-advisories.html
NIST National Vulnerability Database

Elsewhere on this site

Webpack-dev-server
every CVE for this vendor

Info disclosure
same class

CWE-209
other pages naming this weakness

Related CVEs (same products)

High CVE-2026-112085 webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades 2d
Medium CVE-2026-14631 webpack-dev-server vulnerable to denial of service via a malformed Host or Origin header Jul 3, 2026
Medium CVE-2026-14620 webpack-dev-server vulnerable to cross-site request forgery via internal developer endpoints Jul 3, 2026
Medium CVE-2026-9595 webpack-dev-server vulnerable to HMR WebSocket interception via permissive user proxies Jun 15, 2026
Medium CVE-2026-6402 webpack-dev-server vulnerable to cross-origin source code exposure on non-HTTPS origins May 12, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-114348 is "webpack-dev-server vulnerable to information disclosure via Host validation bypass in the open-editor endpoint", rated Medium. It affects Webpack-dev-server (Webpack-dev-server); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 5.3 describes technical severity. EPSS 0.31% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

Comments

Moderated technical discussion. Read the community guidelines.

No comments yet.