High

CVE-2026-112085 — webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades

webpack-dev-server is a development server that provides live reloading for webpack projects. In versions before 5.2.7 and in version 6.0.0, when a proxy entry is configured to forward WebSockets, the server forwards non-HMR WebSocket upgrade requests to the proxy target without validating the Host or Origin headers, so the allowedHosts protection does not apply to those proxied upgrades. A malicious web page visited by a developer can open a cross-origin WebSocket through the dev server and read from and write to the proxied backend, even when the server is bound to loopback. The issue is fixed in webpack-dev-server 5.2.7 and 6.1.0, where proxied WebSocket upgrades pass the same Host and Origin validation as the HMR WebSocket, and users should upgrade to one of those versions or later. As a workaround, omit WebSocket forwarding from proxy entries that do not need it and scope the proxy to specific paths.

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 0.2% (30-day exploitation probability)+1
Technical severity (high)+6

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

0.16%

ahead of 5% of scored CVEs · Oct 22, 2026

Affects

Webpack-dev-server

CVSS base

8.2

High · 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

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.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
Search available logs for exploit probes, 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	< 5.2.7≥ 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

Required

Scope

Changed

Confidentiality

High

Integrity

Low

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
8.2	CVSS 3.1	High	2.8	4.7	ce714d77-add3-4f53-aff5-83d477b104bb via NIST National Vulnerability Database
8.2	CVSS 3.1	High	—	—	openjs via CVE Program (cve.org) e CISA ADP

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

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-346

Other CVEs with this weakness →

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).

web/proxy/WAF logsnetwork IDS/IPS

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 · 8.2
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-cfqc-fj3v-j925
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

CWE-346
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-114348 webpack-dev-server vulnerable to information disclosure via Host validation bypass in the open-editor endpoint 1d
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-2026-112085 is "webpack-dev-server vulnerable to cross-origin WebSocket access via proxied upgrades", rated High. 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 8.2 describes technical severity. EPSS 0.16% 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.

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