How to Fix CVE-2026-20149: Cross-site scripting in Cisco Webex Meetings

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

CVE-2026-20149 is a cross-site scripting in Cisco Cisco Webex Meetings. The fix is to apply the vendor patch noted below.

What is CVE-2026-20149?

A vulnerability in Cisco Webex could have allowed an unauthenticated, remote attacker to conduct a cross-site scripting (XSS) attack. Cisco has addressed this vulnerability, and no customer action is needed.

This vulnerability was due to improper filtering of user-supplied input. Prior to this vulnerability being addressed, an attacker could have exploited this vulnerability by persuading a user to follow a malicious link. A successful exploit could have allowed the attacker to conduct an XSS attack against the targeted user. The CVSS base score is 6.1 (Medium). The official advisory is at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-xss-TZFTbbwN.

Am I affected?

Check the version of Cisco Webex Meetings you are running and compare it against the Affected row above (Cisco Webex Meetings N/A). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:

# Linux package check
dpkg -s cisco-webex-meetings 2>/dev/null | grep -i ^Version
rpm -q cisco-webex-meetings 2>/dev/null
command -v cisco-webex-meetings >/dev/null && cisco-webex-meetings --version 2>/dev/null

# Windows (PowerShell)
Get-Package -Name "*Cisco Webex Meetings*" -ErrorAction SilentlyContinue | Select-Object Name, Version
winget list --name "Cisco Webex Meetings" 2>$null

How to fix CVE-2026-20149

Upgrade Cisco Webex Meetings 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 cisco-webex-meetings
dpkg -s cisco-webex-meetings | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux

sudo dnf upgrade --refresh cisco-webex-meetings -y
# or for older releases:
sudo yum update cisco-webex-meetings -y
rpm -q cisco-webex-meetings

SUSE / openSUSE

sudo zypper refresh
sudo zypper update cisco-webex-meetings
rpm -q cisco-webex-meetings

Complete PowerShell remediation script (Windows)

# Fix script for CVE-2026-20149 affecting Cisco Webex Meetings
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-20149-fix-$(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"
    $pkg = Get-Package -Name "*Cisco Webex Meetings*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

    Write-Host "[2/4] Backup configuration"
    $backup = "C:\Backup\cisco-webex-meetings-$(Get-Date -Format yyyyMMdd)"
    New-Item -ItemType Directory -Force $backup | Out-Null
    Get-ChildItem "C:\ProgramData\Cisco Webex Meetings" -ErrorAction SilentlyContinue |
        Copy-Item -Destination $backup -Recurse -Force -ErrorAction SilentlyContinue

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "Cisco Webex Meetings" --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 "Cisco Webex Meetings"
    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-2026-20149 affecting Cisco Webex Meetings
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-20149-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 cisco-webex-meetings 2>/dev/null | grep -i ^Version || echo "cisco-webex-meetings not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q cisco-webex-meetings || echo "cisco-webex-meetings not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-20149-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/cisco-webex-meetings /etc/cisco-webex-meetings.d /etc/cisco-webex-meetings.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 cisco-webex-meetings
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y cisco-webex-meetings
elif command -v yum >/dev/null; then
    yum update -y cisco-webex-meetings
elif command -v zypper >/dev/null; then
    zypper --non-interactive update cisco-webex-meetings
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s cisco-webex-meetings 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q cisco-webex-meetings
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-2026-20149" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-20149"

Disable the affected service (Linux)

sudo systemctl stop cisco-webex-meetings 2>/dev/null || true
sudo systemctl disable cisco-webex-meetings 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 cisco-webex-meetings 2>/dev/null | grep -i ^Version
rpm -q cisco-webex-meetings 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 "*Cisco Webex Meetings*" | 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

Related fixes

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

• How to Fix CVE-2026-20117: Multiple Cisco Contact Center Products Cross-Site Scripting Vulnerabilities — Multiple Cisco Contact Center Products Cross-Site Scripting Vulnerabilities
• How to Fix CVE-2026-20152: Authentication bypass by primary weakness flaw in Cisco Secure Web Appliance — Authentication bypass by primary weakness flaw in Cisco Secure Web Appliance
• How to Fix CVE-2026-20022: Use of out-of-range pointer offset in Cisco Secure Firewall Adaptive Security. , Use of out-of-range pointer offset in Cisco Secure Firewall Adaptive Security.
• How to Fix CVE-2026-20079: Authentication bypass using an alternate path or channel in Cisco Secure Firewall. , Authentication bypass using an alternate path or channel in Cisco Secure Firewall.
• How to Fix CVE-2026-20107: Insufficient granularity of access control in Cisco Application Policy. , Insufficient granularity of access control in Cisco Application Policy.

Is CVE-2026-20149 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-2026-20149?

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-2026-20149?

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

Where is the official advisory for CVE-2026-20149?

The vendor advisory is at https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-xss-TZFTbbwN. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-20149.

References

• Official vendor advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-webex-xss-TZFTbbwN
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20149
• CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog

*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.*