CVE-2018-18903: Vanilla 2.6.x before 2.6.4 allows remote code execution.

This week

CRITICAL 9.8REMOTEUPGRADE

CVE-2018-18903 is a critical-severity flaw (CVSS 9.8) affecting vanilla. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Vanilla 2.6.x before 2.6.4 allows remote code execution.

Why this priority

Critical severity
EPSS top 8%: very likely to be exploited
Public exploit reference
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	5.2% (top 8%)
CISA exploited list	No
Weakness	CWE-94
Published	2018-11-03
Last modified	2026-06-17

Publisher (CNA): MITRE · Vendor: vanillaforums

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

Am I affected?

Timeline

2018-11-03 05:29 UTCPublished CVE record published
2026-06-17 01:48 UTCUpdated Record last modified

vanillaforums vanilla UPGRADE

Affected: >= 2.6.0 and < 2.6.4

Fixed in: 2.6.4

Safe to downgrade to: a release before 2.6.0

1. Check installed version

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

2. UPGRADE to 2.6.4 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade vanilla

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 2.6.0 (Debian / Ubuntu)

apt-cache madison vanilla sudo apt install vanilla=<VERSION_BEFORE_2.6.0> sudo apt-mark hold vanilla

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

dnf --showduplicates list vanilla sudo dnf downgrade vanilla-<VERSION_BEFORE_2.6.0> sudo dnf versionlock add vanilla

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-2018-18903?

vanilla: upgrade to 2.6.4. Exact commands for each OS are on this page.

Is CVE-2018-18903 being exploited?

CVE-2018-18903 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-2018-18903 affect?

CVE-2018-18903 affects vanilla. Severity is critical (CVSS 9.8). Vanilla 2.6.x before 2.6.4 allows remote code execution.

How urgent is CVE-2018-18903?

Priority 67/100. Critical severity; EPSS top 8%: very likely to be exploited; Public exploit reference; Remotely exploitable, no login, no user action

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References

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