CVE-2026-8134: Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlC

Q: How do I fix CVE-2026-8134?

concrete cms: upgrade to newer than 9.5.0. Exact commands for each OS are on this page.

Q: Is CVE-2026-8134 being exploited?

CVE-2026-8134 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-8134 affect?

CVE-2026-8134 affects concrete cms. Severity is high (CVSS 7.2). Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue administrator with composer form editing r

Routine

HIGH 7.2UPGRADE

CVE-2026-8134 is a high-severity flaw (CVSS 7.2) affecting concrete cms. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue administrator with composer form editing rights can exploit this to include arbitrary readable files on the server. Combined with the file uploader's extension-only validation (which permits PHP code in files saved with image extensions like .png), thi

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.2 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	High
User interaction	None
EPSS exploit chance	0.7% (top 46%)
CISA exploited list	No
Weakness	CWE-23, CWE-98, CWE-434
Published	2026-05-21
Last modified	2026-07-23

Publisher (CNA): ConcreteCMS · Vendor: concretecms

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

Am I affected?

Timeline

2026-05-21 21:16 UTCPublished CVE record published
2026-07-23 16:10 UTCUpdated Record last modified

concretecms concrete cms UPGRADE

Affected: <= 9.5.0

Fixed in: newer than 9.5.0

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy concrete-cms || rpm -q concrete-cms || concrete-cms --version

2. UPGRADE to newer than 9.5.0 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade concrete-cms

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade concrete-cms

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

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-2026-8134?

concrete cms: upgrade to newer than 9.5.0. Exact commands for each OS are on this page.

Is CVE-2026-8134 being exploited?

CVE-2026-8134 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-2026-8134 affect?

CVE-2026-8134 affects concrete cms. Severity is high (CVSS 7.2). Concrete CMS 9.5.0 and below fails to sanitize path traversal sequences in the ptComposerFormLayoutSetControlCustomTemplate field when saving page type composer form layouts. An authenticated rogue administrator with composer form editing r

How urgent is CVE-2026-8134?

Priority 39/100. High severity

Software pages

PHP vulnerabilities

Related CVEs

CVE-2026-18111 MEDIUM 6.1 UPGRADE Concrete CMS 9 before 9.5.3 was vulnerable to stored cross-site scripting (XSS) in the Feature, Feature Link,
CVE-2026-18117 MEDIUM 5.4 UPGRADE Concrete CMS 9.0.0 through 9.5.3 is vulnerable to stored XSS via the custom page alias name (customAliasName)
CVE-2026-68526 MEDIUM 4.3 UPGRADE Concrete CMS before 9.5.3 did not validate an anti-CSRF token in the Calendar event duplicate dialog controlle
CVE-2026-81912 MEDIUM 5.7 UPGRADE Concrete CMS before 9.5.3 is vulnerable to Cross-Site Request Forgery in the Move Multiple Groups feature
CVE-2026-81913 MEDIUM 6.1 UPGRADE Concrete CMS versions 9.5.0 through 9.5.2 are vulnerable to Open Redirect via the rcURL parameter

References

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