Medium Open redirect

CVE-2026-47848 — Reactor Netty WebSocket Client Leaks Credentials On Redirect

In specific scenarios involving WebSocket handshake redirects to a different origin, the Reactor Netty WebSocket client may leak credentials. In order for this to happen, the HTTP client must have been explicitly configured to follow redirects. Reactor Netty 1.3.0 - 1.3.6 Reactor Netty 1.1.0 - 1.2.18 Reactor Netty 1.0.52 and earlier

Published Aug 26, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: vmware

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

Technical severity (medium)+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

—

No EPSS score.

Affects

Broadcom

Reactor Netty

CVSS base

6.1

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

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 (Broadcom Reactor Netty, Spring Reactor Netty).
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 matching the vulnerability class (open redirect), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Broadcom	Reactor Netty	< 1.0.53≥ 1.1.0 and < 1.2.19≥ 1.3.0 and < 1.3.6.1	Vulnerable	NIST National Vulnerability Database
Spring	Reactor Netty	≥ 1.3.0 and ≤ 1.3.6≥ 1.1.0 and ≤ 1.2.18≤ 1.0.52	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

Low

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
6.1	CVSS 3.1	Medium	2.8	2.7	security@vmware.com via NIST National Vulnerability Database
6.1	CVSS 3.1	Medium	—	—	vmware via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N (score shown at the top: security@vmware.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-601 · Open Redirect

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
Affected products added · spring/reactor netty
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 15, 2026
CVSS changed · 6.1
Oct 15, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 15, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 15, 2026 · NIST National Vulnerability Database
CVE published
Aug 26, 2026 · vmware

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

1 on the record

spring.io/security/cve-2026-47848
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Broadcom
every CVE for this vendor

Open redirect
same class

CWE-601
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-47874 Reactor Netty HTTP Server Denial of Service With Pipelined Requests Aug 26, 2026
Medium CVE-2026-47845 Reactor Netty HTTP Server may incorrectly evaluate proxy addresses Aug 26, 2026
Low CVE-2026-47843 Reactor Netty may incorrectly route traffic due to DNS resolver reuse Aug 26, 2026
Low CVE-2026-47844 Reactor Netty HTTP Server Leaks Exception Details Aug 26, 2026
Medium CVE-2026-41715 Reactor Netty HTTP Client Leaks Credentials On Protocol Downgrade Redirect Jun 9, 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 FIRST EPSS score.
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-2026-47848 is "Reactor Netty WebSocket Client Leaks Credentials On Redirect", rated Medium. It affects Reactor Netty (Broadcom); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.1 describes technical severity. 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.