⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● High · CVSS 7.6

How to Fix CVE-2026-27970: Cross-site scripting in angular

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

CVE-2026-27970 is a cross-site scripting in angular angular. The fix is to apply the vendor patch noted below.

⚡ At a glance
Severity7.6 (High)
Actively exploited?No public listing in CISA KEV
Affectedangular >= 21.2.0-next.0, < 21.2.0; angular >= 21.0.0-next.0, < 21.1.6; angular >= 20.0.0-next.0, < 20.3.17; angular >= 19.0.0-next.0, < 19.2.19; angular <= 18.2.14
Fixed inSee vendor advisory
Type (CWE)CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

What is CVE-2026-27970?

Angular is a development platform for building mobile and desktop web applications using TypeScript/JavaScript and other languages. Versions prior to 21.2.0, 21.1.16, 20.3.17, and 19.2.19 have a cross-Site scripting vulnerability in the Angular internationalization (i18n) pipeline. In ICU messages (International Components for Unicode), HTML from translated content was not properly sanitized and could execute arbitrary JavaScript. Angular i18n typically involves three steps, extracting all messages from an application in the source language, sending the messages to be translated, and then merging their translations back into the final source code. Translations are frequently handled by contracts with specific partner companies, and involve sending the source messages to a separate contractor before receiving final translations for display to the end user. If the returned translations have malicious content, it could be rendered into the application and execute arbitrary JavaScript. When successfully exploited, this vulnerability allows for execution of attacker controlled JavaScript in the application origin. Depending on the nature of the application being exploited this could lead to credential exfiltration and/or page vandalism. Several preconditions apply to the attack. The attacker must compromise the translation file (xliff, xtb, etc.). Unlike most XSS vulnerabilities, this issue is not exploitable by arbitrary users. An attacker must first compromise an application's translation file before they can escalate privileges into the Angular application client. The victim application must use Angular i18n, use one or more ICU messages, render an ICU message, and not defend against XSS via a safe content security policy. Versions 21.2.0, 21.1.6, 20.3.17, and 19.2.19 patch the issue. Until the patch is applied, developers should consider reviewing and verifying translated content received from untrusted third parties before incorporating it in an Angular application, enabling strict CSP controls to block unauthorized JavaScript from executing on the page, and enabling Trusted Types to enforce proper HTML sanitization. The CVSS base score is 7.6 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://github.com/angular/angular/security/advisories/GHSA-prjf-86w9-mfqv.

Am I affected?

Check the version of angular you are running and compare it against the Affected row above (angular >= 21.2.0-next.0, < 21.2.0; angular >= 21.0.0-next.0, < 21.1.6; angular >= 20.0.0-next.0, < 20.3.17; angular >= 19.0.0-next.0, < 19.2.19; angular <= 18.2.14). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27970

Upgrade angular 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 angular
dpkg -s angular | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update angular
rpm -q angular

Node.js / npm


# Update the affected package in your project
npm install angular@latest
npm ls angular
npm audit fix

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27970 affecting angular
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27970-fix-$(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"
    $pkg = Get-Package -Name "*angular*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "angular" --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 "angular"
    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-2026-27970 affecting angular
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27970-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 angular 2>/dev/null | grep -i ^Version || echo "angular not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q angular || echo "angular not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27970-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/angular /etc/angular.d /etc/angular.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 angular
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y angular
elif command -v yum >/dev/null; then
    yum update -y angular
elif command -v zypper >/dev/null; then
    zypper --non-interactive update angular
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s angular 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q angular
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-2026-27970" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27970"

Disable the affected service (Linux)


sudo systemctl stop angular 2>/dev/null || true
sudo systemctl disable angular 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 angular 2>/dev/null | grep -i ^Version
rpm -q angular 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 "*angular*" | 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:

Is CVE-2026-27970 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-2026-27970?

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-2026-27970?

7.6 (High). Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N.

Where is the official advisory for CVE-2026-27970?

The vendor advisory is at https://github.com/angular/angular/security/advisories/GHSA-prjf-86w9-mfqv. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27970.

References

*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.*