# CVE-2026-126662: Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, and 6.0.0 before 6.0.6 Filemount Bypass via Edit-Multiple

Status: published. Published: 2026-11-11. Updated: 2026-11-11.

Contao 4.0.0 before 5.3.54, 5.4.0 before 5.7.17, and 6.0.0 before 6.0.6 contains an access control bypass vulnerability that allows filemount-restricted backend users to modify folders outside their filemount via the file manager Edit-Multiple operation. Attackers holding the protected or syncExclude field permission can submit outside folder paths in the IDS parameter to publish protected folders or exclude them from DBAFS synchronization, exposing files for public download.

## Remediation

- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/contao/contao/commit/c01898f99c5d5af50a227ee85f27270c5427f900
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/contao/contao/commit/a104202df2b532bb64805a0856fc94bb0bddbb66
- fix: The reporting source identifies this reference as a patch. Check the advisory for affected versions and supported release branches. (source: CNA: VulnCheck) — https://github.com/contao/contao/commit/240e169441796bb703819ee0e22728708f946b70

## Affected products and versions

- Contao / Contao (contao/core-bundle): ≥ 4.0.0; < 5.3.54 (affected, semver); ≥ 5.4.0-RC1; < 5.7.17 (affected, semver); ≥ 6.0.0-RC1; < 6.0.6 (affected, semver). Source: CNA: VulnCheck

## Severity and prioritization

- CVSS 4.0: 7.1 (high); CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 7.1 (high); CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:N; source: CNA: VulnCheck

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-862

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://github.com/contao/contao/security/advisories/GHSA-9jfh-v443-w3fj (CNA: VulnCheck; vendor-advisory)

- https://github.com/contao/contao/commit/c01898f99c5d5af50a227ee85f27270c5427f900 (CNA: VulnCheck; patch)

- https://github.com/contao/contao/commit/a104202df2b532bb64805a0856fc94bb0bddbb66 (CNA: VulnCheck; patch)

- https://github.com/contao/contao/commit/240e169441796bb703819ee0e22728708f946b70 (CNA: VulnCheck; patch)

- https://github.com/contao/contao/releases/tag/5.3.54 (CNA: VulnCheck; release-notes)

- https://github.com/contao/contao/releases/tag/5.7.17 (CNA: VulnCheck; release-notes)

- https://github.com/contao/contao/releases/tag/6.0.6 (CNA: VulnCheck; release-notes)

- https://github.com/contao/contao/blob/5.3.53/core-bundle/contao/drivers/DC_Folder.php#L1716-L1720 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/contao-4.0.0-before-5.3.54-5.4.0-before-5.7.17-and-6.0.0-before-6.0.6-filemount-bypass-via-edit-multiple (CNA: VulnCheck; third-party-advisory)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-126662; retrieved 2026-11-11; source updated 2026-11-11

Revision: 0d237b45bbaac63816db3ea38a2ec9535c869e171865863fc700e7b13255b248

Canonical: https://y2.dev/cve/CVE-2026-126662

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