⚠ 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 8.2

How to Fix CVE-2026-27193: Information exposure in feathers

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

CVE-2026-27193 is a information exposure in feathersjs feathers. The fix is to apply the vendor patch noted below.

⚡ At a glance
Severity8.2 (High)
Actively exploited?No public listing in CISA KEV
Affectedfeathers < 5.0.40
Fixed inSee vendor advisory
Type (CWE)CWE-200: Exposure of Sensitive Information to an Unauthorized Actor

What is CVE-2026-27193?

Feathersjs is a framework for creating web APIs and real-time applications with TypeScript or JavaScript. In versions 5.0.39 and below, all HTTP request headers are stored in the session cookie, which is signed but not encrypted, exposing internal proxy/gateway headers to clients. The OAuth service stores the complete headers object in the session, then the session is persisted using cookie-session, which base64-encodes the data. While the cookie is signed to prevent tampering, the contents are readable by anyone by simply decoding the base64 value. Under specific deployment configurations (e.g., behind reverse proxies or API gateways), this can lead to exposure of sensitive internal infrastructure details such as API keys, service tokens, and internal IP addresses. This issue has been fixed in version 5.0.40. The CVSS base score is 8.2 (High), which puts this in the upper risk band and warrants a fast patch cycle. The official advisory is at https://github.com/feathersjs/feathers/security/advisories/GHSA-9m9c-vpv5-9g85.

Am I affected?

Check the version of feathers you are running and compare it against the Affected row above (feathers < 5.0.40). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27193

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

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update feathers
rpm -q feathers

Node.js / npm


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

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27193 affecting feathers
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27193-fix-$(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"
    $pkg = Get-Package -Name "*feathers*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "feathers" --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 "feathers"
    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-2026-27193 affecting feathers
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27193-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 feathers 2>/dev/null | grep -i ^Version || echo "feathers not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q feathers || echo "feathers not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27193-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/feathers /etc/feathers.d /etc/feathers.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 feathers
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y feathers
elif command -v yum >/dev/null; then
    yum update -y feathers
elif command -v zypper >/dev/null; then
    zypper --non-interactive update feathers
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s feathers 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q feathers
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-2026-27193" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27193"

Disable the affected service (Linux)


sudo systemctl stop feathers 2>/dev/null || true
sudo systemctl disable feathers 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 feathers 2>/dev/null | grep -i ^Version
rpm -q feathers 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 "*feathers*" | 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-2026-27193 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-2026-27193?

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-2026-27193?

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

Where is the official advisory for CVE-2026-27193?

The vendor advisory is at https://github.com/feathersjs/feathers/security/advisories/GHSA-9m9c-vpv5-9g85. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27193.

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.*