CVE-2022-28805: singlevar in lparser.c in Lua from (including) 5.4.0 up to (excluding) 5.4.4 lacks a certain luaK_exp2anyregup

This week

CRITICAL 9.1REMOTEUPGRADEMITIGATE

CVE-2022-28805 is a critical-severity flaw (CVSS 9.1) affecting lua, fedora. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

singlevar in lparser.c in Lua from (including) 5.4.0 up to (excluding) 5.4.4 lacks a certain luaK_exp2anyregup call, leading to a heap-based buffer over-read that might affect a system that compiles untrusted Lua code.

Why this priority

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

A fixed release or distro patch exists.

Risk facts

CVSS score	9.1 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	3.0% (top 13%)
CISA exploited list	No
Weakness	CWE-125
Published	2022-04-08
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: fedoraproject · lua

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

Am I affected?

Timeline

2022-04-08 06:15 UTCPublished CVE record published
2026-06-17 04:39 UTCUpdated Record last modified

lua lua UPGRADE

Affected: >= 5.4.0 and < 5.4.5

Fixed in: 5.4.5

Safe to downgrade to: a release before 5.4.0

1. Check installed version

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

2. UPGRADE to 5.4.5 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade lua

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 5.4.0 (Debian / Ubuntu)

apt-cache madison lua sudo apt install lua=<VERSION_BEFORE_5.4.0> sudo apt-mark hold lua

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

dnf --showduplicates list lua sudo dnf downgrade lua-<VERSION_BEFORE_5.4.0> sudo dnf versionlock add lua

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.

fedoraproject fedora MITIGATE

Affected: 35 · 36

Fixed in: no fixed release known

Safe to downgrade to: a release before 35

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-2022-28805?

lua: upgrade to 5.4.5; fedora: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2022-28805 being exploited?

CVE-2022-28805 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-2022-28805 affect?

CVE-2022-28805 affects lua, fedora. Severity is critical (CVSS 9.1). singlevar in lparser.c in Lua from (including) 5.4.0 up to (excluding) 5.4.4 lacks a certain luaK_exp2anyregup call, leading to a heap-based buffer over-read that might affect a system that compiles untrusted Lua code.

How urgent is CVE-2022-28805?

Priority 64/100. Critical severity; Public exploit reference; Remotely exploitable, no login, no user action

Related CVEs

CVE-2022-33099 HIGH 7.5 UPGRADE MITIGATE An issue in the component luaG_runerror of Lua v5.4.4 and below leads to a heap-buffer overflow when a recursi
CVE-2021-45985 HIGH 7.5 UPGRADE In Lua 5.4.3, an erroneous finalizer called during a tail call leads to a heap-based buffer over-read.
CVE-2021-44964 MEDIUM 6.3 UPGRADE Use after free in garbage collector and finalizer of lgc.c in Lua interpreter 5.4.0~5.4.3 allows attackers to
CVE-2021-44647 MEDIUM 5.5 DOWNGRADE MITIGATE Lua v5.4.3 and above are affected by SEGV by type confusion in funcnamefromcode function in ldebug.c which can

References

← Back to latest CVEs