Skip to main content
VulnerabilityPublished

CVE-2026-13400: Simply Schedule Appointments (WordPress plugin) · Cross-Site Scripting (XSS)

Affects Simply Schedule Appointments (WordPress plugin)Source CVE Database V5

0

Not known to be exploited · CVSS 6.1 Medium : upgrade to 1.6.12.4 when convenient.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score
6.1Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 16% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 1.6.12.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Jul 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

What to do

Upgrade Simply Schedule Appointments (WordPress plugin) to 1.6.12.4.

Affected software

ProductAffectedFixed in
Simply Schedule AppointmentsAffected
  • <1.6.12.4
Fixed in
  • 1.6.12.4

AI-suggested

The vulnerability is fixed starting from version 1.6.12.4 by correcting the sanitization order with the wp_kses_post() filter. Until patching, avoid exposing notification content to untrusted users or disable the affected plugin if possible.

Description

Simply Schedule Appointments is vulnerable to unauthenticated Stored Cross-Site Scripting in all versions up to and including 1.6.12.2. The root cause is a sanitization-ordering defect: the rendered notification content is decoded back into live HTML after it has already passed through the Simply Schedule Appointments WordPress plugin before 1.6.12.4's wp_kses_post() filter, so a double-encoded payload survives intake and is reintroduced as an executable element at render time.

References

Community reviews

Loading reviews…