CVE-2026-30827: express-rate-limit is a basic rate-limiting middleware for Express

This week

HIGH 7.5REMOTEUPGRADE

CVE-2026-30827 is a high-severity flaw (CVSS 7.5) affecting express-rate-limit. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

express-rate-limit is a basic rate-limiting middleware for Express. In versions starting from 8.0.0 and prior to versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0, the default keyGenerator in express-rate-limit applies IPv6 subnet masking (/56 by default) to all addresses that net.isIPv6() returns true for. This includes IPv4-mapped IPv6 addresses (::ffff:x.x.x.x), which Node.js returns as request.ip on dual-stack servers. Because the first 80 bits of all

Why this priority

High severity
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	7.5 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-770
Published	2026-03-07
Last modified	2026-06-17

Publisher (CNA): GitHub, Inc. · Vendor: express-rate-limit project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-07 06:16 UTCPublished CVE record published
2026-06-17 10:32 UTCUpdated Record last modified

express-rate-limit project express-rate-limit UPGRADE

Affected: >= 8.0.0 and < 8.0.2 · >= 8.2.0 and < 8.2.2 · 8.1.0

Fixed in: 8.0.2, 8.2.2

Safe to downgrade to: a release before 8.0.0

1. Check installed version

apt-cache policy express-rate-limit || rpm -q express-rate-limit || express-rate-limit --version

2. UPGRADE to 8.0.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade express-rate-limit

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade express-rate-limit

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 8.0.0 (Debian / Ubuntu)

apt-cache madison express-rate-limit sudo apt install express-rate-limit=<VERSION_BEFORE_8.0.0> sudo apt-mark hold express-rate-limit

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

dnf --showduplicates list express-rate-limit sudo dnf downgrade express-rate-limit-<VERSION_BEFORE_8.0.0> sudo dnf versionlock add express-rate-limit

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.

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-2026-30827?

express-rate-limit: upgrade to 8.0.2, 8.2.2. Exact commands for each OS are on this page.

Is CVE-2026-30827 being exploited?

CVE-2026-30827 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-2026-30827 affect?

CVE-2026-30827 affects express-rate-limit. Severity is high (CVSS 7.5). express-rate-limit is a basic rate-limiting middleware for Express. In versions starting from 8.0.0 and prior to versions 8.0.2, 8.1.1, 8.2.2, and 8.3.0, the default keyGenerator in express-rate-limit applies IPv6 subnet masking (/56 by def

How urgent is CVE-2026-30827?

Priority 47/100. High severity; Public exploit reference; Remotely exploitable, no login, no user action

Software pages

Node.js vulnerabilities

References

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