● Medium · CVSS 6.4

How to Fix CVE-2026-27735: Path traversal in servers

Q: What is the CVSS score for CVE-2026-27735?

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

Q: Where is the official advisory for CVE-2026-27735?

The vendor advisory is at [https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6v](https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6v). The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27735.

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

CVE-2026-27735 is a path traversal in modelcontextprotocol servers. The fix is to apply the vendor patch noted below.

⚡ At a glance


Severity	6.4 (Medium)
Actively exploited?	No public listing in CISA KEV
Affected	servers < 2026.1.14
Fixed in	See vendor advisory
Type (CWE)	CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

What is CVE-2026-27735?

Model Context Protocol Servers is a collection of reference implementations for the model context protocol (MCP). In mcp-server-git versions prior to 2026.1.14, the git_add tool did not validate that file paths provided in the files argument were within the repository boundaries. Because the tool used GitPython's repo.index.add() rather than the Git CLI, relative paths containing ../ sequences that resolve outside the repository were accepted and staged into the Git index. Users are advised to upgrade to 2026.1.14 or newer to remediate this issue. The CVSS base score is 6.4 (Medium). The official advisory is at https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6v.

Am I affected?

Check the version of servers you are running and compare it against the Affected row above (servers < 2026.1.14). If your build sits inside the affected range, you must patch.

Run the version check that fits your platform:


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


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

How to fix CVE-2026-27735

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

RHEL / CentOS / Rocky / AlmaLinux


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

SUSE / openSUSE


sudo zypper refresh
sudo zypper update servers
rpm -q servers

Complete PowerShell remediation script (Windows)


# Fix script for CVE-2026-27735 affecting servers
# Run as administrator. Detect -> backup -> upgrade -> verify -> log.

$ErrorActionPreference = "Stop"
$LogPath  = "C:\Logs\CVE-2026-27735-fix-$(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"
    $pkg = Get-Package -Name "*servers*" -ErrorAction SilentlyContinue
    if ($pkg) { $pkg | Format-Table Name, Version }
    else { Write-Host "Not detected via Get-Package; try winget list" }

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

    Write-Host "[3/4] Apply the upgrade to See vendor advisory"
    winget upgrade --name "servers" --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 "servers"
    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-2026-27735 affecting servers
# Detect -> backup -> upgrade -> verify -> log.

set -euo pipefail
LOG="/var/log/cve-2026-27735-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 servers 2>/dev/null | grep -i ^Version || echo "servers not installed via dpkg"
elif command -v rpm >/dev/null; then
    rpm -q servers || echo "servers not installed via rpm"
fi

echo "[2/4] Backup configuration"
BACKUP="/root/backup-cve-2026-27735-$(date +%Y%m%d)"
mkdir -p "$BACKUP"
for d in /etc/servers /etc/servers.d /etc/servers.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 servers
elif command -v dnf >/dev/null; then
    dnf upgrade --refresh -y servers
elif command -v yum >/dev/null; then
    yum update -y servers
elif command -v zypper >/dev/null; then
    zypper --non-interactive update servers
fi

echo "[4/4] Verify the patched build"
if command -v dpkg >/dev/null; then
    dpkg -s servers 2>/dev/null | grep -i ^Version
elif command -v rpm >/dev/null; then
    rpm -q servers
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-2026-27735" -Direction Inbound -Action Block -Protocol TCP -LocalPort 80,443 -RemoteAddress Any -Enabled True
Get-NetFirewallRule -DisplayName "Block-CVE-2026-27735"

Disable the affected service (Linux)


sudo systemctl stop servers 2>/dev/null || true
sudo systemctl disable servers 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 servers 2>/dev/null | grep -i ^Version
rpm -q servers 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 "*servers*" | 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-2026-24370: Critical Vulnerability in The Grid — Critical Vulnerability in The Grid
How to Fix CVE-2026-25814: Critical Vulnerability in assessment-placipy — Critical Vulnerability in assessment-placipy
How to Fix CVE-2026-24778: Critical Vulnerability in Ghost , Critical Vulnerability in Ghost
How to Fix CVE-2026-2652: Authentication Bypass in mlflow/mlflow , Authentication Bypass in mlflow/mlflow
How to Fix CVE-2026-26731: Stack Buffer Overflow in n/a , Stack Buffer Overflow in n/a

Is CVE-2026-27735 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-2026-27735?

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-2026-27735?

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

Where is the official advisory for CVE-2026-27735?

The vendor advisory is at https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6v. The NVD record is at https://nvd.nist.gov/vuln/detail/CVE-2026-27735.

References

Official vendor advisory: https://github.com/modelcontextprotocol/servers/security/advisories/GHSA-vjqx-cfc4-9h6v
NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-27735
CISA KEV catalog: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
Additional reference: https://github.com/modelcontextprotocol/servers/pull/3164

*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.*