CVE-2026-46727: An issue was discovered in Ruby 4 before 4.0.5

This month

HIGH 8.1REMOTEUPGRADE

CVE-2026-46727 is a high-severity flaw (CVSS 8.1) affecting ruby. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

An issue was discovered in Ruby 4 before 4.0.5. A race condition leading to a use-after-free in the pthread-based getaddrinfo timeout handler (rb_getaddrinfo in ext/socket/raddrinfo.c) allows a remote attacker who can delay DNS responses near the user-specified timeout to crash a Ruby process that calls Addrinfo.getaddrinfo(..., timeout:) or Socket.tcp(..., resolv_timeout:). Memory-corruption-based exploitation is theoretically possible. The atta

Why this priority

High severity
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	8.1 (High)
Attack vector	Network (remote)
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.5% (top 59%)
CISA exploited list	No
Weakness	CWE-362
Published	2026-05-22
Last modified	2026-07-23

Publisher (CNA): MITRE · Vendor: ruby-lang

Last updated 2026-07-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-05-22 18:16 UTCPublished CVE record published
2026-07-23 16:10 UTCUpdated Record last modified

ruby-lang ruby UPGRADE

Affected: >= 4.0.0 and < 4.0.5

Fixed in: 4.0.5

Safe to downgrade to: a release before 4.0.0

1. Check installed version

apt-cache policy ruby || rpm -q ruby || ruby --version

2. UPGRADE to 4.0.5 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade ruby

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade ruby

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 4.0.0 (Debian / Ubuntu)

apt-cache madison ruby sudo apt install ruby=<VERSION_BEFORE_4.0.0> sudo apt-mark hold ruby

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

dnf --showduplicates list ruby sudo dnf downgrade ruby-<VERSION_BEFORE_4.0.0> sudo dnf versionlock add ruby

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-2026-46727?

ruby: upgrade to 4.0.5. Exact commands for each OS are on this page.

Is CVE-2026-46727 being exploited?

CVE-2026-46727 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-2026-46727 affect?

CVE-2026-46727 affects ruby. Severity is high (CVSS 8.1). An issue was discovered in Ruby 4 before 4.0.5. A race condition leading to a use-after-free in the pthread-based getaddrinfo timeout handler (rb_getaddrinfo in ext/socket/raddrinfo.c) allows a remote attacker who can delay DNS responses ne

How urgent is CVE-2026-46727?

Priority 44/100. High severity; Remotely exploitable, no login, no user action

Software pages

Ruby vulnerabilities

References

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