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CVE-2026-81754 fernandot CVE debrief

The Vigilant – 100% Free Security Suite: Firewall, 2FA, Login, Headers, Scanner… plugin for WordPress is vulnerable to Stored Cross-Site Scripting via User-Agent Header in all versions up to, and including, 2.10.2. This vulnerability allows unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. The vulnerability is caused by insufficient input sanitization and output escaping. The malicious payload is delivered passively by any unauthenticated visitor who triggers a failed login attempt with a crafted User-Agent header, requiring no further interaction from the attacker once stored. Defenders should prioritize

Vendor
fernandot
Product
Vigilant – 100% Free Security Suite: Firewall, 2FA, Login, Headers, Scanner…
CVSS
HIGH 7.2
CISA KEV
Not listed in stored evidence
Original CVE published
2026-09-11
Original CVE updated
2026-09-11
Advisory published
2026-09-11
Advisory updated
2026-09-11

Who should care

Defenders responsible for WordPress installations using the Vigilant plugin, especially those allowing unauthenticated login attempts, should assess exposure and prioritize verifying and mitigating this vulnerability.

Why it matters

CVE-2026-81754 is a Stored Cross-Site Scripting vulnerability in the Vigilant plugin for WordPress, allowing unauthenticated attackers to inject arbitrary web scripts. Defenders should prioritize verifying exposure, implementing mitigations, and monitoring for potential attacks.

  • Defenders must verify exposure of WordPress installations using the Vigilant plugin
  • Assess the feasibility of injecting arbitrary web scripts through crafted User-Agent headers
  • Implement input sanitization and output escaping for User-Agent headers to prevent exploitation
  • Monitor for suspicious login attempts and injected scripts to detect potential attacks

Technical summary

The Vigilant – 100% Free Security Suite: Firewall, 2FA, Login, Headers, Scanner… plugin for WordPress is vulnerable to Stored Cross-Site Scripting via User-Agent Header in all versions up to, and including, 2.10.2 due to insufficient input sanitization and output escaping. This allows unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Defensive priority

Defenders should prioritize verifying exposure of WordPress installations using the Vigilant plugin, especially those allowing unauthenticated login attempts, and assess the feasibility of injecting arbitrary web scripts through crafted User-Agent headers.

Recommended defensive actions

  • Verify exposure of WordPress installations using the Vigilant plugin
  • Assess the feasibility of injecting arbitrary web scripts through crafted User-Agent headers
  • Implement input sanitization and output escaping for User-Agent headers
  • Monitor for suspicious login attempts and injected scripts
  • Review compensating controls for exposed systems while remediation is scheduled and verified
  • Check relevant monitoring, detection, and logs for exposed assets that need extra review
  • Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record and NVD entry provide details on the vulnerability, including its CVSS score of 7.2 and HIGH severity. The vulnerability allows unauthenticated attackers to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-81754 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-81754

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-81754 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-81754

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.