CVE-2026-90916: Joomla! Core - [20260906] - Core - Improper ACL checks in content history comparison view in Joomla 4.0.0-5.4.

Routine

LOW 2.7UPGRADE

CVE-2026-90916 is a low-severity flaw (CVSS 2.7) affecting joomla\!. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Joomla! Core - [20260906] - Core - Improper ACL checks in content history comparison view in Joomla 4.0.0-5.4.8, 6.0.0-6.1.3 - An improper access check allows unauthorized users to view inaccessible contents.

Why this priority

No elevated risk signals yet

A fixed release or distro patch exists.

Risk facts

CVSS score	2.7 (Low)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.2% (top 92%)
CISA exploited list	No
Weakness	CWE-284
Published	2026-09-29
Last modified	2026-10-06

Publisher (CNA): Joomla! Project · Vendor: joomla

Last updated 2026-10-06 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-29 17:17 UTCPublished CVE record published
2026-10-06 16:34 UTCUpdated Record last modified

joomla joomla\! UPGRADE

Affected: >= 4.0.0 and < 5.4.8 · >= 6.0.0 and < 6.1.3

Fixed in: 5.4.8, 6.1.3

Safe to downgrade to: a release before 4.0.0

1. Check installed version

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

2. UPGRADE to 5.4.8 (Debian / Ubuntu)

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

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade joomla

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 joomla sudo apt install joomla=<VERSION_BEFORE_4.0.0> sudo apt-mark hold joomla

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

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

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.

Advisories and coverage

Official advisories

Joomla Security Centre: [20260906] - Core - Improper ACL checks in content history comparison view 2026-09-25

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-2026-90916?

joomla\!: upgrade to 5.4.8, 6.1.3. Exact commands for each OS are on this page.

Is CVE-2026-90916 being exploited?

CVE-2026-90916 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-2026-90916 affect?

CVE-2026-90916 affects joomla\!. Severity is low (CVSS 2.7). Joomla! Core - [20260906] - Core - Improper ACL checks in content history comparison view in Joomla 4.0.0-5.4.8, 6.0.0-6.1.3 - An improper access check allows unauthorized users to view inaccessible contents.

How urgent is CVE-2026-90916?

Priority 11/100. No elevated risk signals yet.

Software pages

Joomla vulnerabilities

Related CVEs

CVE-2026-48958 HIGH 8.8 UPGRADE An improper access check allows unauthorized users to create custom fields via webservices endpoints.
CVE-2026-48948 HIGH 8.8 UPGRADE An improper access check allows user to download vcard exports of com_contact contacts that are inaccessible.
CVE-2026-48957 HIGH 8.8 UPGRADE An improper access check allows unauthorized users to access com_privacy datasets.
CVE-2026-48955 MEDIUM 6.5 UPGRADE An improper access check allows unauthorized users to access workflow stage and transition information.
CVE-2026-48949 MEDIUM 6.1 UPGRADE Lack of validation leads to an XSS vulnerability in the MFA management views.

References

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