CVE-2023-28756: A ReDoS issue was discovered in the Time component through 0.2.1 in Ruby through 3.2.1

This month

MEDIUM 5.3REMOTEWATCHLISTUPGRADEDOWNGRADEMITIGATE

CVE-2023-28756 is a medium-severity flaw (CVSS 5.3) affecting ruby, time, debian linux. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A ReDoS issue was discovered in the Time component through 0.2.1 in Ruby through 3.2.1. The Time parser mishandles invalid URLs that have specific characters. It causes an increase in execution time for parsing strings to Time objects. The fixed versions are 0.1.1 and 0.2.2.

Why this priority

Remotely exploitable, no login, no user action
On your watchlist

A fixed release or distro patch exists.

Risk facts

CVSS score	5.3 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	2.5% (top 16%)
CISA exploited list	No
Weakness	CWE-1333
Published	2023-03-31
Last modified	2026-06-17

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

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

Am I affected?

Timeline

2023-03-31 04:15 UTCPublished CVE record published
2026-06-17 05:48 UTCUpdated Record last modified

ruby-lang ruby UPGRADE

Affected: <= 2.7.7

Fixed in: newer than 2.7.7

Safe to downgrade to: no unaffected older release

1. Check installed version

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

2. UPGRADE to newer than 2.7.7 (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.

ruby-lang time DOWNGRADE

Affected: 0.1.0 · 0.2.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 0.1.0

1. Check installed version

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

2. No fixed release: DOWNGRADE to a release before 0.1.0 (Debian / Ubuntu)

apt-cache madison time sudo apt install time=<VERSION_BEFORE_0.1.0> sudo apt-mark hold time

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

dnf --showduplicates list time sudo dnf downgrade time-<VERSION_BEFORE_0.1.0> sudo dnf versionlock add time

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.

debian debian linux MITIGATE

Affected: 10.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 10.0

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

fedoraproject fedora MITIGATE

Affected: 36 · 37 · 38

Fixed in: no fixed release known

Safe to downgrade to: a release before 36

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

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-2023-28756?

ruby: upgrade to newer than 2.7.7; time: downgrade or apply the listed mitigation; debian linux: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2023-28756 being exploited?

CVE-2023-28756 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-2023-28756 affect?

CVE-2023-28756 affects ruby, time, debian linux. Severity is medium (CVSS 5.3). A ReDoS issue was discovered in the Time component through 0.2.1 in Ruby through 3.2.1. The Time parser mishandles invalid URLs that have specific characters. It causes an increase in execution time for parsing strings to Time objects. The

How urgent is CVE-2023-28756?

Priority 50/100. Remotely exploitable, no login, no user action; On your watchlist

Software pages

Debian vulnerabilities · Ruby vulnerabilities

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References

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