● Medium · CVSS 5.7

How to Fix CVE-2026-27638: Missing authorization in actual

Q: What is the CVSS score for CVE-2026-27638?

5.7 (Medium). Vector: `CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:P`.

Q: Where is the official advisory for CVE-2026-27638?

The vendor advisory is at [https://github.com/actualbudget/actual/security/advisories/GHSA-qmjj-p7m9-wjrv](https://github.com/actualbudget/actual/security/advisories/GHSA-qmjj-p7m9-wjrv). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27638.

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

CVE-2026-27638 is a missing authorization in actualbudget actual. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	5.7 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	actual < 26.2.1
Fixed in	See vendor advisory
Type (CWE)	CWE-862: Missing Authorization

What is CVE-2026-27638?

Actual is a local-first personal finance tool. Prior to version 26.2.1, in multi-user mode (OpenID), the sync API endpoints (/sync/*) don't verify that the authenticated user owns or has access to the file being operated on. Any authenticated user can read, modify, and overwrite any other user's budget files by providing their file ID. Version 26.2.1 patches the issue. The CVSS base score is 5.7 (Medium). The official advisory is at https://github.com/actualbudget/actual/security/advisories/GHSA-qmjj-p7m9-wjrv.

Am I affected?

Check the version of actual you are running and compare it against the Affected row above (actual < 26.2.1). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27638

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

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update actual
rpm -q actual

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27638 affecting actual
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27638-fix-$(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"
    $pkg = Get-Package -Name "*actual*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "actual" --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 "actual"
    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-2026-27638 affecting actual
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27638-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 actual 2>/dev/null | grep -i ^Version || echo "actual not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q actual || echo "actual not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27638-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/actual /etc/actual.d /etc/actual.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 actual
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y actual
elif command -v yum >/dev/null; then
    yum update -y actual
elif command -v zypper >/dev/null; then
    zypper --non-interactive update actual
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s actual 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q actual
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-2026-27638" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27638"

Disable the affected service (Linux)


sudo systemctl stop actual 2>/dev/null || true
sudo systemctl disable actual 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 actual 2>/dev/null | grep -i ^Version
rpm -q actual 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 "*actual*" | 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-2026-34738: AVideo (Bundle Sibling) — AVideo (Bundle Sibling)
How to Fix CVE-2026-26365: Cwe-444 inconsistent interpretation of http requests ('http request/response. — Cwe-444 inconsistent interpretation of http requests ('http request/response.
How to Fix CVE-2026-24898: Authentication bypass in openemr , Authentication bypass in openemr
How to Fix CVE-2026-34462: Stack-based Buffer Overflow in Sandboxie , Stack-based Buffer Overflow in Sandboxie
How to Fix CVE-2026-32604: Improper input validation in spinnaker , Improper input validation in spinnaker

Is CVE-2026-27638 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-2026-27638?

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-2026-27638?

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

Where is the official advisory for CVE-2026-27638?

The vendor advisory is at https://github.com/actualbudget/actual/security/advisories/GHSA-qmjj-p7m9-wjrv. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27638.

References

Official vendor advisory: https://github.com/actualbudget/actual/security/advisories/GHSA-qmjj-p7m9-wjrv
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27638
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://github.com/actualbudget/actual/commit/9966c024cb75f57943193cac8e42f401efed9d08
Additional reference: https://github.com/actualbudget/actual/releases/tag/v26.2.1

*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.*