Security readout for executives and security teams
Plain-English summary
CVE-2021-4302 is a cross-site scripting issue in phpwcms through 1.9.26 involving SVG file handling. A remote authenticated attacker could cause script execution in a user’s browser. The business impact is usually limited, but it can support session misuse, content tampering, or phishing inside a trusted CMS context.
Executive priority
Treat this as a routine but necessary CMS security update. It is not flagged for known active exploitation, but authenticated XSS in a public-facing CMS can create reputational and account-risk exposure if left unpatched.
Technical view
The sources classify this as CWE-79 XSS in slackero phpwcms SVG File Handler, affecting versions 1.9.0 through 1.9.26. CVSS v2 is 4.0 with network access, low complexity, single authentication, partial integrity impact, and no confidentiality or availability impact. Version 1.9.27 and commit b39db9c7ad3800f319195ff0e26a0981395b1c54 address it.
Likely exposure
Exposure is most likely where phpwcms 1.9.26 or older is deployed and authenticated users can upload or manage SVG content. Public anonymous exposure is not supported by the provided CVSS vector because authentication is required.
Exploitation context
The bundle says the attack can be initiated remotely, but it does not cite active exploitation. The CVE is not listed as KEV in the provided data. Technical details are limited because the affected subcomponent path or exact trigger is not identified.
Researcher notes
The available record identifies SVG file handling but not the exact vulnerable code path in the summary. Validation should focus on version and patch presence rather than reproducing the issue. Do not assume anonymous exploitability; the CVSS vector indicates single authentication.
Mitigation direction
- Upgrade phpwcms to version 1.9.27 or later.
- Confirm commit b39db9c7ad3800f319195ff0e26a0981395b1c54 is present if patching manually.
- Restrict SVG upload and management permissions to trusted users.
- Check vendor guidance before applying compensating controls not named in sources.
Validation and detection
- Inventory phpwcms deployments and record exact versions.
- Verify affected systems are not running 1.9.0 through 1.9.26.
- Confirm the 1.9.27 release or patch commit is deployed.
- Review CMS roles with SVG upload or file management permissions.
- Check recent CMS changes for unexpected SVG uploads or content edits.
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-79: User-session and phishing behavior lookup
Client-side and session-facing weaknesses should be reviewed alongside initial-access and user-execution behaviors. 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-2021-4302 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
- Medium
- CVSS
- 4 (2.0)
- Known Exploited
- No
- Published
Vector: AV:N/AC:L/Au:S/C:N/I:P/A:N
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.
AV:N/AC:L/Au:S/C:N/I:P/A:N82.9Primary CVE scoreVulnerability scoring details
Base CVSS 2.0 score
4MediumVector: AV:N/AC:L/Au:S/C:N/I:P/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://vuldb.com/?id.217419CVE reference · vdb-entry, technical-description
- https://vuldb.com/?ctiid.217419CVE reference · signature, permissions-required
- https://github.com/slackero/phpwcms/commit/b39db9c7ad3800f319195ff0e26a0981395b1c54CVE reference · patch
- https://github.com/slackero/phpwcms/releases/tag/v1.9.27CVE reference · patch
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 Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.