● Medium · CVSS 6.3

How to Fix CVE-2026-23747: Stack buffer overflow in Firmware SDK

Q: What is the CVSS score for CVE-2026-23747?

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

Q: Where is the official advisory for CVE-2026-23747?

The vendor advisory is at [https://secmate.dev/disclosures/SECMATE-2025-0015](https://secmate.dev/disclosures/SECMATE-2025-0015). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-23747.

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

CVE-2026-23747 is a stack buffer overflow in Golioth Firmware SDK. The fix is to upgrade to Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332.

⚡ At a glance


Severity	6.3 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	Firmware SDK 0.10.0 to <0.22.0
Fixed in	Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332
Type (CWE)	CWE-121 Stack-based Buffer Overflow

What is CVE-2026-23747?

Golioth Firmware SDK version 0.10.0 prior to 0.22.0, fixed in commit 48f521b, contain a stack-based buffer overflow in Payload Utils. The golioth_payload_as_int() and golioth_payload_as_float() helpers copy network-supplied payload data into fixed-size stack buffers using memcpy() with a length derived from payload_size. The only length checks are guarded by assert(); in release builds, the asserts are compiled out and memcpy() may copy an unbounded payload_size. Payloads larger than 12 bytes (int) or 32 bytes (float) can overflow the stack, resulting in a crash/denial of service. This is reachable via LightDB State on_payload with a malicious server or MITM. The CVSS base score is 6.3 (Medium). The official advisory is at https://secmate.dev/disclosures/SECMATE-2025-0015.

Am I affected?

Check the version of Firmware SDK you are running and compare it against the Affected row above (Firmware SDK 0.10.0 to <0.22.0). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-23747

Upgrade Firmware SDK to a patched build: Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332. 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 firmware-sdk
dpkg -s firmware-sdk | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update firmware-sdk
rpm -q firmware-sdk

Node.js / npm


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

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-23747 affecting Firmware SDK
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-23747-fix-$(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"
    $pkg = Get-Package -Name "*Firmware SDK*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332"
    winget upgrade --name "Firmware SDK" --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 "Firmware SDK"
    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-2026-23747 affecting Firmware SDK
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-23747-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 firmware-sdk 2>/dev/null | grep -i ^Version || echo "firmware-sdk not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q firmware-sdk || echo "firmware-sdk not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-23747-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/firmware-sdk /etc/firmware-sdk.d /etc/firmware-sdk.conf; do
    [ -e "$d" ] && cp -a "$d" "$BACKUP/" || true
done

echo "[3/4] Apply the upgrade (target: Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332)"
if command -v apt-get >/dev/null; then
    apt-get update
    apt-get install --only-upgrade -y firmware-sdk
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y firmware-sdk
elif command -v yum >/dev/null; then
    yum update -y firmware-sdk
elif command -v zypper >/dev/null; then
    zypper --non-interactive update firmware-sdk
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s firmware-sdk 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q firmware-sdk
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-2026-23747" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-23747"

Disable the affected service (Linux)


sudo systemctl stop firmware-sdk 2>/dev/null || true
sudo systemctl disable firmware-sdk 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 firmware-sdk 2>/dev/null | grep -i ^Version
rpm -q firmware-sdk 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 "*Firmware SDK*" | Select-Object Name, Version
Get-HotFix | Sort-Object InstalledOn -Descending | Select-Object -First 5

Expected: the reported version is at or above Firmware SDK 48f521bcc0187ada2b9cbdad31dc380e6c7b7332. Restart the affected service (systemctl restart <service> on Linux, or restart the Windows service) so it loads the patched binary.

Frequently asked questions

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Is CVE-2026-23747 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-2026-23747?

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-2026-23747?

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

Where is the official advisory for CVE-2026-23747?

The vendor advisory is at https://secmate.dev/disclosures/SECMATE-2025-0015. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-23747.

References

Official vendor advisory: https://secmate.dev/disclosures/SECMATE-2025-0015
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-23747
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://blog.secmate.dev/posts/golioth-vulnerabilities-disclosure/
Additional reference: https://github.com/golioth/golioth-firmware-sdk/releases/tag/v0.22.0
Additional reference: https://github.com/golioth/golioth-firmware-sdk/commit/48f521bcc0187ada2b9cbdad31dc380e6c7b7332

*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.*