Security readout for executives and security teams
Plain-English summary
CVE-2021-37626 affects Contao CMS. A trusted-looking back end editing feature could be abused by an untrusted privileged back end user to load PHP files through insert tags. The issue is serious because successful abuse can affect confidentiality, integrity, and availability, but exposure depends on both vulnerable versions and risky back end permissions.
Executive priority
Prioritize remediation for public Contao sites with delegated back end users, shared editorial teams, or contractor access. Patch during the next urgent maintenance window if exposure conditions apply. If only highly trusted administrators have access, urgency is reduced but the fixed version should still be scheduled.
Technical view
Affected Contao 4.x versions allow PHP file inclusion through insert tags entered in the Contao back end. The CVSS v3.1 score is 7.2 high, vector AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H, mapped to CWE-94. The vendor fixed it in 4.4.56, 4.9.18, and 4.11.7.
Likely exposure
Likely exposed systems are Contao installations running affected 4.x versions where untrusted back end users can modify fields displayed on the front end. Systems without such users or permissions have lower practical exposure based on the advisory condition.
Exploitation context
The source bundle does not show CISA KEV listing or active exploitation. The attack requires high privileges in the Contao back end, so the main concern is malicious insiders, compromised editor accounts, or delegated administrative access with front end content modification rights.
Researcher notes
The key exposure condition is authorization context, not just version presence. Validate both affected version ranges and whether untrusted back end users can edit front end-rendered fields. Do not assume unauthenticated exploitation from the provided CVSS vector or advisory text.
Mitigation direction
- Update Contao to 4.4.56, 4.9.18, 4.11.7, or later supported releases.
- If updating is delayed, disable login for untrusted back end users.
- Review back end roles that can edit fields displayed on the front end.
- Remove unnecessary high-privilege access from contractors, editors, and inactive accounts.
- Check Contao vendor guidance before applying any alternative workaround.
Validation and detection
- Inventory Contao instances and record exact installed versions.
- Confirm no instance runs 4.0.0-4.4.55, 4.5.0-4.9.17, or 4.10.0-4.11.6.
- Review back end user lists for untrusted or inactive accounts.
- Verify which roles can modify fields rendered on the front end.
- Document whether vendor-fixed versions are deployed in production.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-94: Code execution behavior lookup
Code execution and unsafe deserialization weaknesses often justify reviewing execution behavior and process telemetry. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2021-37626 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- High
- CVSS
- 7.2 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H1.25.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
7.2HighVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://github.com/contao/contao/security/advisories/GHSA-r6mv-ppjc-4hgrCVE reference · x_refsource_CONFIRM
- https://contao.org/en/security-advisories/php-file-inclusion-via-insert-tags.htmlCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Improper Control of Generation of Code ('Code Injection')
Improper Control of Generation of Code ('Code Injection') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.