Skip to main content
Mallory
High

Stored XSS in Bookly WordPress plugin via bookly-customer-full-name cookie

IdentifiersCVE-2026-5513CWE-79· Improper Neutralization of Input…

CVE-2026-5513 is a stored cross-site scripting vulnerability in the Online Scheduling and Appointment Booking System – Bookly plugin for WordPress. Affected versions are up to and including 27.2. The issue is caused by insufficient input sanitization and output escaping of data from the 'bookly-customer-full-name' cookie. An unauthenticated attacker can supply malicious script content through that cookie, and the payload may later be rendered in application pages without proper neutralization, resulting in stored JavaScript execution in victims' browsers when they access the affected page.

Share:
For your environment

Are you exposed to this one?

Mallory correlates every CVE against your assets, your vendors, and active adversary campaigns. Know which vulnerabilities matter for you, not just which ones are loud.

ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows unauthenticated attackers to execute arbitrary JavaScript in the browser context of users who view the injected page. This can enable session hijacking, credential theft, unauthorized actions performed in the victim's session, content manipulation, phishing overlays, and broader client-side compromise within the affected WordPress site.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, disable the 'Remember personal information in cookies' setting, as exploitation requires this feature and it is disabled by default. Additionally, monitor for suspicious script injection in booking-related pages, restrict exposure of affected functionality where feasible, and consider deploying compensating controls such as a restrictive Content Security Policy to reduce XSS impact.

Remediation

Patch, then assume compromise.

Update the Bookly plugin to a version newer than 27.2 once a vendor patch is available. The underlying fix should ensure strict sanitization of the 'bookly-customer-full-name' cookie value on input and context-appropriate output escaping wherever the value is rendered. After patching, review affected pages and stored data for malicious injected content and clear any attacker-controlled values that may persist.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

ACTIVITY FEED

Recent activity

8 sources tracked across advisories and community write-ups. News coverage will land here when it surfaces.

No news coverage yet. Advisories and community discussion only.

What this page doesn’t show

The version that knows your environment.

This page is what’s public. Mallory adds the parts that aren’t: which of your assets are affected, which adversaries are exploiting it right now, which detections to deploy, and what to do tonight.
Exposure mapping

Query your assets running an affected version, and investigate the blast radius.

Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity8

Community discussion across Reddit, Mastodon, and other social sources.