CVE-2024-27456: rack-cors (aka Rack CORS Middleware) 2.0.1 has 0666 permissions for the .rb files.

This week

CRITICAL 9.1REMOTEDOWNGRADE

CVE-2024-27456 is a critical-severity flaw (CVSS 9.1) affecting rack cors middleware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

rack-cors (aka Rack CORS Middleware) 2.0.1 has 0666 permissions for the .rb files.

Why this priority

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

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.8% (top 44%)
CISA exploited list	No
Weakness	CWE-200
Published	2024-02-26
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: rylabs

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

Am I affected?

Timeline

2024-02-26 16:28 UTCPublished CVE record published
2026-06-17 07:19 UTCUpdated Record last modified

rylabs rack cors middleware DOWNGRADE

Affected: 2.0.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 2.0.1

1. Check installed version

apt-cache policy rack-cors-middleware || rpm -q rack-cors-middleware || rack-cors-middleware --version

2. No fixed release: DOWNGRADE to a release before 2.0.1 (Debian / Ubuntu)

apt-cache madison rack-cors-middleware sudo apt install rack-cors-middleware=<VERSION_BEFORE_2.0.1> sudo apt-mark hold rack-cors-middleware

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list rack-cors-middleware sudo dnf downgrade rack-cors-middleware-<VERSION_BEFORE_2.0.1> sudo dnf versionlock add rack-cors-middleware

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-2024-27456?

rack cors middleware: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2024-27456 being exploited?

CVE-2024-27456 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-2024-27456 affect?

CVE-2024-27456 affects rack cors middleware. Severity is critical (CVSS 9.1). rack-cors (aka Rack CORS Middleware) 2.0.1 has 0666 permissions for the .rb files.

How urgent is CVE-2024-27456?

Priority 56/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

References

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