Security readout for executives and security teams
Plain-English summary
CVE-2021-39345 is a stored cross-site scripting flaw in the HAL WordPress plugin through version 2.1.1. An authenticated administrator could save script content that later runs in a browser. The business risk is mainly to WordPress sites with delegated or compromised admin access, especially where WordPress normally blocks unfiltered HTML.
Executive priority
Treat this as a moderate-priority WordPress hygiene issue, not an emergency internet-wide exploit. Prioritize sites with many administrators, multisite operations, or known admin account risk, then confirm patch or removal options.
Technical view
The issue is CWE-79 in the HAL plugin's wp-hal.php, where several parameters lacked sufficient validation and sanitization. The CVSS 3.1 score is 5.5 with high privileges required, network access, low complexity, changed scope, and low confidentiality and integrity impact. Sources identify affected versions up to and including 2.1.1.
Likely exposure
Exposure is limited to WordPress installations running the HAL plugin version 2.1.1 or earlier. The source specifically notes multisite installations where unfiltered_html is disabled for administrators, and sites where unfiltered_html is disabled.
Exploitation context
The bundle does not show CISA KEV listing or active exploitation evidence. Exploitation requires administrative user access, which lowers broad internet risk but remains relevant for compromised admin accounts, delegated administrators, or multisite environments with constrained HTML permissions.
Researcher notes
Evidence supports authenticated stored XSS only. The bundle does not provide exploit status, detailed affected parameters, or a specific fixed version. Use the Trac changeset and vendor advisories to confirm patch behavior before making remediation claims.
Mitigation direction
- Inventory WordPress sites for the HAL plugin and version.
- Check Wordfence, WordPress Trac, and vendor guidance for the fixed release status.
- Upgrade beyond HAL 2.1.1 if a fixed release is available.
- Restrict administrator access to trusted users only.
- Disable or remove HAL where it is not business-required.
Validation and detection
- Confirm whether HAL is installed on each WordPress site.
- Verify installed HAL versions are not 2.1.1 or earlier.
- Review admin accounts for unnecessary or stale privileged users.
- Check affected sites for unexpected stored script content in HAL-managed settings.
- Document whether unfiltered_html is disabled in each relevant WordPress environment.
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-2021-39345 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
- 5.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/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.
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N2.32.7Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
5.5MediumVector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
Source materials
- CVE List V5 sourceCVE List V5
- https://www.wordfence.com/vulnerability-advisories/#CVE-2021-39345CVE reference · x_refsource_MISC
- https://github.com/BigTiger2020/word-press/blob/main/HAL.mdCVE reference · x_refsource_MISC
- https://plugins.trac.wordpress.org/changeset?sfp_email=&sfph_mail=&reponame=&old=2614075%40hal&new=2614075%40hal&sfp_email=&sfph_mail=CVE 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 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.