# CVE-2026-128335: Contao before 5.3.54, 5.7.17, and 6.0.6 Session Invalidation Failure on 2FA Change

Status: published. Published: 2026-11-13. Updated: 2026-11-13.

Contao 4.6.0 before 5.3.54, 5.4.0-RC1 before 5.7.17, and 6.0.0-RC1 before 6.0.6 fails to invalidate existing user sessions when two-factor authentication is enabled or disabled. Because Contao\User::isEqualTo() and serialized session data omit two-factor state, attackers already holding a session keep it after the owner changes 2FA settings.

## 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/7e7c821ce6c41c02ae85b3d9f8eff5039de3fe1e
- 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/7618a5757347a30168139e74c7b326e3e296059d
- 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/843da308056402d94ae2dbb999959f9e2ce71fe1

## Affected products and versions

- Contao / Contao (contao/core-bundle): ≥ 4.6.0; < 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: 2.1 (low); CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N; source: CNA: VulnCheck

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N; source: CNA: VulnCheck

- CVSS 4.0: 2.1 (low); CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X; source: NVD: disclosure@vulncheck.com

- CVSS 3.1: 3.7 (low); CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:U/C:L/I:L/A:N; source: NVD: disclosure@vulncheck.com

- CISA KEV: No listing in collected sources

- EPSS: Not available

- SSVC: Not available

- Weaknesses: CWE-613

## Exploit evidence

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

## References

- https://github.com/contao/contao/security/advisories/GHSA-5mg3-mv6j-57wc (CNA: VulnCheck; vendor-advisory)

- https://github.com/contao/contao/commit/7e7c821ce6c41c02ae85b3d9f8eff5039de3fe1e (CNA: VulnCheck; patch)

- https://github.com/contao/contao/commit/7618a5757347a30168139e74c7b326e3e296059d (CNA: VulnCheck; patch)

- https://github.com/contao/contao/commit/843da308056402d94ae2dbb999959f9e2ce71fe1 (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/library/Contao/User.php#L413-L446 (CNA: VulnCheck; technical-description)

- https://www.vulncheck.com/advisories/contao-before-5.3.54-5.7.17-and-6.0.6-session-invalidation-failure-on-2fa-change (CNA: VulnCheck; third-party-advisory)

- https://github.com/contao/contao/blob/5.3.53/core-bundle/contao/library/Contao/User.php#L413-L446 (disclosure@vulncheck.com)

- https://github.com/contao/contao/commit/7618a5757347a30168139e74c7b326e3e296059d (disclosure@vulncheck.com)

- https://github.com/contao/contao/commit/7e7c821ce6c41c02ae85b3d9f8eff5039de3fe1e (disclosure@vulncheck.com)

- https://github.com/contao/contao/commit/843da308056402d94ae2dbb999959f9e2ce71fe1 (disclosure@vulncheck.com)

- https://github.com/contao/contao/releases/tag/5.3.54 (disclosure@vulncheck.com)

- https://github.com/contao/contao/releases/tag/5.7.17 (disclosure@vulncheck.com)

- https://github.com/contao/contao/releases/tag/6.0.6 (disclosure@vulncheck.com)

- https://github.com/contao/contao/security/advisories/GHSA-5mg3-mv6j-57wc (disclosure@vulncheck.com)

- https://www.vulncheck.com/advisories/contao-before-5.3.54-5.7.17-and-6.0.6-session-invalidation-failure-on-2fa-change (disclosure@vulncheck.com)

## Provenance

- CNA: VulnCheck: https://www.cve.org/CVERecord?id=CVE-2026-128335; retrieved 2026-11-13; source updated 2026-11-13

- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-128335; retrieved 2026-11-13; source updated 2026-11-13

Revision: 4df7bceca6897753ebb59f9c06cc50c4bdd8f3c8ba58ab7be4cfb55353c02a27

Canonical: https://y2.dev/cve/CVE-2026-128335

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