● Medium · CVSS 6.4

How to Fix CVE-2026-2355: Cross-site scripting in My Calendar – Accessible Event Manager

Q: What is the CVSS score for CVE-2026-2355?

6.4 (Medium). Vector: `CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N`.

Q: Where is the official advisory for CVE-2026-2355?

The vendor advisory is at [https://www.wordfence.com/threat-intel/vulnerabilities/id/03d5c82e-f82f-4156-bb3e-e6eb365a6c36?source=cve](https://www.wordfence.com/threat-intel/vulnerabilities/id/03d5c82e-f82f-4156-bb3e-e6eb365a6c36?source=cve). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-2355.

By Sai Kiran Pandrala. Last verified: 2026-05-25.

CVE-2026-2355 is a cross-site scripting in joedolson My Calendar – Accessible Event Manager. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	6.4 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	My Calendar – Accessible Event Manager 0 to <=3.7.3
Fixed in	See vendor advisory
Type (CWE)	CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

What is CVE-2026-2355?

The My Calendar – Accessible Event Manager plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the template attribute of the [my_calendar_upcoming] shortcode in all versions up to, and including, 3.7.3. This is due to the use of stripcslashes() on user-supplied shortcode attribute values in the mc_draw_template() function, which decodes C-style hex escape sequences (e.g., \x3c to <) at render time, bypassing WordPress's wp_kses_post() content sanitization that runs at save time. 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. The CVSS base score is 6.4 (Medium). The official advisory is at https://www.wordfence.com/threat-intel/vulnerabilities/id/03d5c82e-f82f-4156-bb3e-e6eb365a6c36?source=cve.

Am I affected?

Check the version of My Calendar – Accessible Event Manager you are running and compare it against the Affected row above (My Calendar – Accessible Event Manager 0 to <=3.7.3). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


# Linux package check
dpkg -s my-calendar-accessible-event-manager 2>/dev/null | grep -i ^Version
rpm -q my-calendar-accessible-event-manager 2>/dev/null
command -v my-calendar-accessible-event-manager >/dev/null && my-calendar-accessible-event-manager --version 2>/dev/null


# Windows (PowerShell)
Get-Package -Name "*My Calendar – Accessible Event Manager*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "My Calendar – Accessible Event Manager" 2>$null

How to fix CVE-2026-2355

Upgrade My Calendar – Accessible Event Manager to a patched build: See vendor advisory. The vendor advisory is the source of truth for the exact fixed version.

Ubuntu / Debian


sudo apt-get update
sudo apt-get install --only-upgrade my-calendar-accessible-event-manager
dpkg -s my-calendar-accessible-event-manager | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


sudo dnf upgrade --refresh my-calendar-accessible-event-manager -y
# or for older releases:
sudo yum update my-calendar-accessible-event-manager -y
rpm -q my-calendar-accessible-event-manager

SUSE / openSUSE


sudo zypper refresh
sudo zypper update my-calendar-accessible-event-manager
rpm -q my-calendar-accessible-event-manager

PHP / Composer


composer update joedolson/my-calendar-accessible-event-manager 2>/dev/null || composer update
composer show | head -20

WordPress


# Update via WP-CLI
wp plugin update --all
wp core update

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-2355 affecting My Calendar – Accessible Event Manager
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-2355-fix-$(Get-Date -Format yyyyMMdd-HHmmss).log"
New-Item -ItemType Directory -Force (Split-Path $LogPath) | Out-Null
Start-Transcript -Path $LogPath -Append

try {
    Write-Host "[1/4] Detect installed version"
    $pkg = Get-Package -Name "*My Calendar – Accessible Event Manager*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

    Write-Host "[2/4] Backup configuration"
    $backup = "C:\Backup\my-calendar-accessible-event-manager-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\My Calendar – Accessible Event Manager" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "My Calendar – Accessible Event Manager" --silent --accept-source-agreements --accept-package-agreements
    if ($LASTEXITCODE -ne 0) {
        # Fallback: pull latest via OS update channel
        Install-Module -Name PSWindowsUpdate -Force -SkipPublisherCheck -ErrorAction SilentlyContinue
        Import-Module PSWindowsUpdate
        Install-WindowsUpdate -MicrosoftUpdate -AcceptAll -IgnoreReboot
    }

    Write-Host "[4/4] Verify the patched build"
    winget list --name "My Calendar – Accessible Event Manager"
    Write-Host "Patch applied. Reboot if prompted."
    exit 0
} catch {
    Write-Error "Patch failed: $_"
    exit 1
} finally {
    Stop-Transcript
}

Complete Bash remediation script (Linux)


#!/usr/bin/env bash
# Fix script for CVE-2026-2355 affecting My Calendar – Accessible Event Manager
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-2355-fix-$(date +%Y%m%d-%H%M%S).log"
exec > >(tee -a "$LOG") 2>&1

echo "[1/4] Detect installed version"
if command -v dpkg >/dev/null; then
    dpkg -s my-calendar-accessible-event-manager 2>/dev/null | grep -i ^Version || echo "my-calendar-accessible-event-manager not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q my-calendar-accessible-event-manager || echo "my-calendar-accessible-event-manager not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-2355-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/my-calendar-accessible-event-manager /etc/my-calendar-accessible-event-manager.d /etc/my-calendar-accessible-event-manager.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: See vendor advisory)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y my-calendar-accessible-event-manager
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y my-calendar-accessible-event-manager
elif command -v yum >/dev/null; then
    yum update -y my-calendar-accessible-event-manager
elif command -v zypper >/dev/null; then
    zypper --non-interactive update my-calendar-accessible-event-manager
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s my-calendar-accessible-event-manager 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q my-calendar-accessible-event-manager
fi
echo "Done. Restart any service that loaded the old library."

If you can't patch immediately

Apply at least one of the following inline controls until you can deploy the patched build. None replace the upgrade.

Restrict exposure with nftables (Linux)


# Allow only trusted CIDR to reach the affected service ports
sudo nft add table inet filter 2>/dev/null || true
sudo nft 'add chain inet filter input { type filter hook input priority 0 ; }' 2>/dev/null || true
sudo nft 'add rule inet filter input tcp dport {80, 443} ip saddr != 10.0.0.0/8 drop'
sudo nft list ruleset

Block at the host firewall (Windows)


New-NetFirewallRule -DisplayName "Block-CVE-2026-2355" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-2355"

Disable the affected service (Linux)


sudo systemctl stop my-calendar-accessible-event-manager 2>/dev/null || true
sudo systemctl disable my-calendar-accessible-event-manager 2>/dev/null || true

If the vendor advisory lists an official workaround, prefer that wording verbatim. If no workaround is published, the only safe remediation is the patch.

How to verify the fix worked

After upgrading, confirm the installed version matches the patched build and that no old library is still loaded by a long-running process.


# Linux
dpkg -s my-calendar-accessible-event-manager 2>/dev/null | grep -i ^Version
rpm -q my-calendar-accessible-event-manager 2>/dev/null || true
# Pid map check for old library handles
sudo lsof +c0 2>/dev/null | grep -i "DEL.*lib" || true


# Windows
Get-Package -Name "*My Calendar – Accessible Event Manager*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above See vendor advisory. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

Other vulnerabilities in the same area that are worth patching alongside this one:

How to Fix CVE-2026-7096: OS Command Injection in HG3 — OS Command Injection in HG3
How to Fix CVE-2026-42339: Server-Side Request Forgery (SSRF) in new-api — Server-Side Request Forgery (SSRF) in new-api
How to Fix CVE-2026-28096: Improper control of filename for include/require statement in php program ('php. , Improper control of filename for include/require statement in php program ('php.
How to Fix CVE-2026-32265: Amazon S3 for Craft CMS has an Information Disclosure in aws-s3 , Amazon S3 for Craft CMS has an Information Disclosure in aws-s3
How to Fix CVE-2026-45346: Cross-Site Scripting in open-webui , Cross-Site Scripting in open-webui

Is CVE-2026-2355 actively exploited?

There is no public confirmation of exploitation in the wild listed in CISA KEV at the time of this writing. Patch anyway. Public exploits commonly follow disclosure within weeks.

Do I need to reboot after patching CVE-2026-2355?

For kernel and OS-level updates, yes. For most userland packages a systemctl restart <service> is enough on Linux, and restarting the Windows service or app on Windows. Any process that loaded the old library keeps using it until restarted.

What is the CVSS score for CVE-2026-2355?

6.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:L/I:L/A:N.

Where is the official advisory for CVE-2026-2355?

The vendor advisory is at https://www.wordfence.com/threat-intel/vulnerabilities/id/03d5c82e-f82f-4156-bb3e-e6eb365a6c36?source=cve. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-2355.

References

Official vendor advisory: https://www.wordfence.com/threat-intel/vulnerabilities/id/03d5c82e-f82f-4156-bb3e-e6eb365a6c36?source=cve
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-2355
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.7.2/my-calendar-shortcodes.php#L112
Additional reference: https://plugins.trac.wordpress.org/browser/my-calendar/tags/3.7.2/my-calendar-templates.php#L83
Additional reference: https://plugins.trac.wordpress.org/browser/my-calendar/trunk/my-calendar-templates.php#L83

*Written by Sai Kiran Pandrala. Assembled from the official vendor advisory, NVD record, and CISA KEV listing on 2026-05-25. Always confirm against the vendor's advisory before applying changes in production.*