⚠ Reference material — not professional advice. Test in staging, back up first, verify against your specific version. Use your own judgment for your environment.
● Medium · CVSS 6.6

How to Fix CVE-2026-27794: Unsafe deserialization in langgraph-checkpoint

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

CVE-2026-27794 is a unsafe deserialization in langchain-ai langgraph-checkpoint. The fix is to apply the vendor patch noted below.

⚡ At a glance
Severity6.6 (Medium)
Actively exploited?No public listing in CISA KEV
Affectedlanggraph-checkpoint < 4.0.0
Fixed inSee vendor advisory
Type (CWE)CWE-502: Deserialization of Untrusted Data

What is CVE-2026-27794?

LangGraph Checkpoint defines the base interface for LangGraph checkpointers. Prior to version 4.0.0, a Remote Code Execution vulnerability exists in LangGraph's caching layer when applications enable cache backends that inherit from BaseCache and opt nodes into caching via CachePolicy. Prior to langgraph-checkpoint 4.0.0, BaseCache defaults to JsonPlusSerializer(pickle_fallback=True). When msgpack serialization fails, cached values can be deserialized via pickle.loads(...). Caching is not enabled by default. Applications are affected only when the application explicitly enables a cache backend (for example by passing cache=... to StateGraph.compile(...) or otherwise configuring a BaseCache implementation), one or more nodes opt into caching via CachePolicy, and the attacker can write to the cache backend (for example a network-accessible Redis instance with weak/no auth, shared cache infrastructure reachable by other tenants/services, or a writable SQLite cache file). An attacker must be able to write attacker-controlled bytes into the cache backend such that the LangGraph process later reads and deserializes them. This typically requires write access to a networked cache (for example a network-accessible Redis instance with weak/no auth or shared cache infrastructure reachable by other tenants/services) or write access to local cache storage (for example a writable SQLite cache file via permissive file permissions or a shared writable volume). Because exploitation requires write access to the cache storage layer, this is a post-compromise / post-access escalation vector. LangGraph Checkpoint 4.0.0 patches the issue. The CVSS base score is 6.6 (Medium). The official advisory is at https://github.com/langchain-ai/langgraph/security/advisories/GHSA-mhr3-j7m5-c7c9.

Am I affected?

Check the version of langgraph-checkpoint you are running and compare it against the Affected row above (langgraph-checkpoint < 4.0.0). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27794

Upgrade langgraph-checkpoint 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 langgraph-checkpoint
dpkg -s langgraph-checkpoint | grep -i ^Version

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update langgraph-checkpoint
rpm -q langgraph-checkpoint

Node.js / npm


# Update the affected package in your project
npm install langgraph-checkpoint@latest
npm ls langgraph-checkpoint
npm audit fix

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27794 affecting langgraph-checkpoint
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27794-fix-$(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"
    $pkg = Get-Package -Name "*langgraph-checkpoint*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "langgraph-checkpoint" --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 "langgraph-checkpoint"
    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-2026-27794 affecting langgraph-checkpoint
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27794-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 langgraph-checkpoint 2>/dev/null | grep -i ^Version || echo "langgraph-checkpoint not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q langgraph-checkpoint || echo "langgraph-checkpoint not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27794-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/langgraph-checkpoint /etc/langgraph-checkpoint.d /etc/langgraph-checkpoint.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 langgraph-checkpoint
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y langgraph-checkpoint
elif command -v yum >/dev/null; then
    yum update -y langgraph-checkpoint
elif command -v zypper >/dev/null; then
    zypper --non-interactive update langgraph-checkpoint
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s langgraph-checkpoint 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q langgraph-checkpoint
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-2026-27794" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27794"

Disable the affected service (Linux)


sudo systemctl stop langgraph-checkpoint 2>/dev/null || true
sudo systemctl disable langgraph-checkpoint 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 langgraph-checkpoint 2>/dev/null | grep -i ^Version
rpm -q langgraph-checkpoint 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 "*langgraph-checkpoint*" | 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-2026-27794 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-2026-27794?

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-2026-27794?

6.6 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H.

Where is the official advisory for CVE-2026-27794?

The vendor advisory is at https://github.com/langchain-ai/langgraph/security/advisories/GHSA-mhr3-j7m5-c7c9. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27794.

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.*