The WPComplete plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'empty' Shortcode Attribute in all versions up to, and including, 2.9.9.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level access and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This requires the premium version of the software in order to exploit. Please note this only affects the pro version.
CVE-2026-77820
MEDIUMPre-NVD 6.46.4
EchelonGraph scoreLOW confidence
This medium-severity CVE scores 6.4 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
Triggered by: NVD CVSS baseline
Sources: secondary
6.4EG
EchelonGraph verdictMonitorLow exploitation likelihood right now — keep watching.
- Lower severity and no public exploit yet
CISA-KEV: Not listedEPSS PROB: —CVSS: 6.4Exploit: None knownExposed: 0
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 6.4
- EG Score
- 6.4(low)
- EG Risk
- 33(Track)EG Risk 33/100SSVC: Track
EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).
How it’s computedSeverity64% × 45%Exploitation0% × 40%Automatability30% × 15%Action: Routine — remediate on your standard cadence. - EPSS PROB
- —
- EPSS %ILE
- —
- KEV
- Not listed
Published
September 19, 2026
Last Modified
September 19, 2026
References (5)
- security@wordfencehttps://plugins.trac.wordpress.org/browser/wpcomplete/tags/2.9.5.7/includes/class-wpcomplete.php#L305
- security@wordfencehttps://plugins.trac.wordpress.org/browser/wpcomplete/tags/2.9.5.7/public/class-wpcomplete-public.php#L1692
- security@wordfencehttps://plugins.trac.wordpress.org/browser/wpcomplete/tags/2.9.5.7/public/class-wpcomplete-public.php#L1802
- security@wordfencehttps://plugins.trac.wordpress.org/browser/wpcomplete/tags/2.9.5.7/public/class-wpcomplete-public.php#L1859
- security@wordfencehttps://www.wordfence.com/threat-intel/vulnerabilities/id/5b91bb81-b5e4-4a50-833b-e2e98ccc09ff?source=cve
Vendor Advisories for CVE-2026-77820(1)
These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.
Weakness Classification(1)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 3× in last 7d / 3× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-09-19 02:29 UTCEG score recompute
- 2026-09-19 01:36 UTCEG score recompute
- 2026-09-19 01:35 UTCMITRE cvelistV5first tracked
Related CVEs(same CWE)
Frequently asked(4)
What is CVE-2026-77820?
CVE-2026-77820 is a medium vulnerability published on September 19, 2026. The WPComplete plugin for WordPress is vulnerable to Stored Cross-Site Scripting via 'empty' Shortcode Attribute in all versions up to, and including, 2.9.9.0 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with contributor-level…
When was CVE-2026-77820 disclosed?
CVE-2026-77820 was first published in the National Vulnerability Database on September 19, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
What is the CVSS score of CVE-2026-77820?
CVE-2026-77820 has a CVSS v3 base score of 6.4 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-77820?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-77820, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.
Dependency Blast Radius
Explore the affected products and dependency analysis for CVE-2026-77820
Is Your Infrastructure Affected by CVE-2026-77820?
EchelonGraph automatically scans your cloud infrastructure and maps CVE exposure using blast radius analysis.