Security readout for executives and security teams
Plain-English summary
A WordPress plugin called Post Index can let an attacker trick an authenticated site administrator into saving malicious script into site settings. If successful, that script can run later in users' browsers and expose data or change site behavior. The sources do not state active exploitation.
Executive priority
Treat this as a high-priority WordPress plugin exposure for any site using Post Index. It is not KEV-listed in the provided data, but stored XSS in an admin-driven workflow can still create meaningful business risk, especially on public websites.
Technical view
CVE-2021-34637 is a CSRF flaw in Post Index's OptionsPage function in php/settings.php, affecting versions up to and including 0.7.5. The reported result is stored XSS through arbitrary web script injection. The CVSS 3.1 score is 8.8 with network attack vector and required user interaction.
Likely exposure
Exposure is limited to WordPress sites running the iTux Post Index plugin at version 0.7.5 or earlier. Risk is highest where administrators remain logged in and can be induced to visit attacker-controlled content.
Exploitation context
The source bundle says KEV is false and provides no cited evidence of active exploitation. The attack requires user interaction and abuses CSRF to change plugin settings, leading to stored XSS. No exploit details or confirmed campaigns are provided.
Researcher notes
Evidence identifies the vulnerable area as OptionsPage in php/settings.php and classifies the weakness as CWE-352. The bundle does not name a patch version, mitigation advisory, exploit publication, or exploitation in the wild, so validation should focus on asset presence, version, and suspicious stored content.
Mitigation direction
- Inventory WordPress sites for the Post Index plugin and version.
- Check vendor or WordPress plugin guidance for a fixed release.
- Disable or remove affected plugin versions if no trusted fix is available.
- Limit administrator sessions and access until remediation is complete.
- Review site security controls for CSRF and stored XSS detection coverage.
Validation and detection
- Confirm whether Post Index is installed on each WordPress site.
- Verify the installed plugin version is later than 0.7.5, if a fixed version exists.
- Review plugin settings for unexpected script content or unauthorized changes.
- Check WordPress audit logs for suspicious administrator setting updates.
- Confirm remediation decisions are documented for each affected site.
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-352: 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-2021-34637 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
- 8.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/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:N/UI:R/S:U/C:H/I:H/A:H2.85.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
8.8HighVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://www.wordfence.com/vulnerability-advisories/#CVE-2021-34637CVE reference · x_refsource_MISC
- https://plugins.trac.wordpress.org/browser/post-index/trunk/php/settings.php#L86CVE 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.
Cross-Site Request Forgery (CSRF)
Cross-Site Request Forgery (CSRF) represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.