CVE-2026-47848: In specific scenarios involving WebSocket handshake redirects to a different origin, the Reactor Netty WebSock

Routine

MEDIUM 6.1UPGRADE

CVE-2026-47848 is a medium-severity flaw (CVSS 6.1) affecting reactor netty. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	0.3% (top 82%)
CISA exploited list	No
Weakness	CWE-601
Published	2026-08-26
Last modified	2026-09-04

Publisher (CNA): VMware · Vendor: broadcom

Last updated 2026-09-04 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-26 20:17 UTCPublished CVE record published
2026-09-04 19:09 UTCUpdated Record last modified

broadcom reactor netty UPGRADE

Affected: < 1.0.53 · >= 1.1.0 and < 1.2.19 · >= 1.3.0 and < 1.3.6.1

Fixed in: 1.0.53, 1.2.19, 1.3.6.1

Safe to downgrade to: a release before 1.1.0

1. Check installed version

apt-cache policy reactor-netty || rpm -q reactor-netty || reactor-netty --version

2. UPGRADE to 1.0.53 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade reactor-netty

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade reactor-netty

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 1.1.0 (Debian / Ubuntu)

apt-cache madison reactor-netty sudo apt install reactor-netty=<VERSION_BEFORE_1.1.0> sudo apt-mark hold reactor-netty

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list reactor-netty sudo dnf downgrade reactor-netty-<VERSION_BEFORE_1.1.0> sudo dnf versionlock add reactor-netty

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Advisories and coverage

Official advisories

Spring Security Advisories: cve-2026-47848 - MEDIUM - Reactor Netty WebSocket Client Leaks Credentials On Redirect 2026-08-20

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-47848?

reactor netty: upgrade to 1.0.53, 1.2.19, 1.3.6.1. Exact commands for each OS are on this page.

Is CVE-2026-47848 being exploited?

CVE-2026-47848 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-47848 affect?

CVE-2026-47848 affects reactor netty. Severity is medium (CVSS 6.1). 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 redire

How urgent is CVE-2026-47848?

Priority 26/100. No elevated risk signals yet.

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References

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