● Medium · CVSS 5.3

How to Fix CVE-2026-23907: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Q: Is CVE-2026-23907 being actively exploited?

Not at the time of writing. It is not listed in CISA's Known Exploited Vulnerabilities catalog. That status can change, so monitor the vendor advisory and the KEV catalog if the system is exposed.

Q: How severe is CVE-2026-23907?

CVSS rates it 5.3 (Medium). Use that score to set your patch priority next to the other items in your queue.

Q: Do I have to take Apache PDFBox Examples offline to apply the patch?

It depends on the deployment. High-availability or clustered installs can usually patch one node at a time with no full outage. Standalone installs typically need a short restart. Always follow the vendor's documented upgrade steps.

Q: What if my vulnerability scanner still flags CVE-2026-23907 after I patch?

Re-run the scan after a service restart, then confirm the scanner's plugin set is up to date. Some scanners detect by banner version only and lag the official fix metadata by a release.

Other vulnerabilities in the same area that are worth patching alongside this one:

How to Fix CVE-2026-42779: CWE-502 Deserialization of Untrusted Data in Apache MINA — CWE-502 Deserialization of Untrusted Data in Apache MINA
How to Fix CVE-2026-41873: CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling') — CWE-444 Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
How to Fix CVE-2026-43975: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') , Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
How to Fix CVE-2026-42440: Memory Allocation with Excessive Size Value in Apache OpenNLP , Memory Allocation with Excessive Size Value in Apache OpenNLP
How to Fix CVE-2026-42811: Improper Neutralization of Special Elements used in an Expression Language State , Improper Neutralization of Special Elements used in an Expression Language State

*By Sai Kiran Pandrala*

⚡ At a glance


Severity	CVSS 5.3, Medium
Actively exploited?	No
Affected	Apache Software Foundation Apache PDFBox Examples (2.0.24 <= 2.0.35, 3.0.0 <= 3.0.6)
Fixed in	See vendor advisory
Type (CWE)	CWE-22: CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

What is CVE-2026-23907?

This issue affects the

ExtractEmbeddedFiles example in Apache PDFBox: from 2.0.24 through 2.0.35, from 3.0.0 through 3.0.6. The ExtractEmbeddedFiles example contains a path traversal vulnerability (CWE-22) because

the filename that is obtained from

PDComplexFileSpecification.getFilename() is appended to the extraction path. Users who have copied this example into their production code should

review it to ensure that the extraction path is acceptable.

In practical terms, a successful attacker gets unauthorized file reads or writes through path traversal. There is no confirmed in-the-wild exploitation listed in CISA's KEV catalog at the time of writing, but the CVSS rating still warrants prompt patching.

Am I affected?

You're affected if you run Apache Software Foundation Apache PDFBox Examples at any version in the Affected row above. Use these probes to find your installed build:


# Confirm the installed version via your package manager
dpkg -l | grep -i apache   # Debian/Ubuntu
rpm -qa | grep -i apache   # RHEL/CentOS/Rocky

How to fix CVE-2026-23907

The primary fix is to upgrade to the patched build listed in the Fixed in row above (See vendor advisory). Pick the platform that matches your install and run the commands below.

Linux (Ubuntu / Debian)


# Vendor advisory: https://github.com/JoakimBulow/
sudo apt-get update
sudo apt-get install --only-upgrade apache-pdfbox-examples
# Confirm the installed version meets or exceeds <patched-version>
dpkg -s apache-pdfbox-examples | grep ^Version

Linux (RHEL / CentOS / Rocky)


sudo dnf upgrade --security apache-pdfbox-examples -y
rpm -q apache-pdfbox-examples

Windows (PowerShell, admin)


# Vendor advisory: https://github.com/JoakimBulow/
# Try winget first
winget upgrade --id 'Apache Software Foundation.Apache PDFBox Examples' --silent --accept-source-agreements --accept-package-agreements
# If winget does not know the product, download the patched installer from the vendor and:
Start-Process -FilePath "$env:TEMP\ApachePDFBoxExamples-<patched-version>.msi" -ArgumentList '/qn /norestart' -Wait

PowerShell script (Windows) - detect, back up, upgrade, verify, log


# Vendor advisory: https://github.com/JoakimBulow/
# Run as Administrator
$ErrorActionPreference = 'Stop'
$log = "$env:ProgramData\ApachePDFBoxExamples-Patch-CVE-2026-23907.log"
function Write-Log($msg) { "$(Get-Date -Format s)  $msg" | Tee-Object -FilePath $log -Append }

Write-Log "Starting CVE-2026-23907 remediation for Apache Software Foundation Apache PDFBox Examples"

# 1. Detect: replace the path/version probe with one valid for your install
$installed = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Apache*' } |
    Select-Object -First 1 -ExpandProperty Version)
Write-Log "Detected version: $installed"

if (-not $installed) {
    Write-Log "Product not installed on this host; nothing to do."
    return
}
if ([version]$installed -ge [version]'<patched-version>') {
    Write-Log "Already at fixed version $installed; no action needed."
    return
}

# 2. Backup configuration to a timestamped folder
$backup = "$env:ProgramData\ApachePDFBoxExamples-Backup-$(Get-Date -Format yyyyMMdd-HHmm)"
New-Item -ItemType Directory -Path $backup -Force | Out-Null
# Adjust the source path to match your install
$src = "$env:ProgramFiles\Apache Software Foundation\Apache PDFBox Examples"
if (Test-Path $src) { Copy-Item -Path $src -Destination $backup -Recurse -Force }
Write-Log "Backed up config to $backup"

# 3. Apply the patched installer (place the verified file on a share or staging path)
$installer = "$env:TEMP\ApachePDFBoxExamples-<patched-version>.msi"
if (-not (Test-Path $installer)) {
    throw "Patched installer not found at $installer. Stage it from your software repo first."
}
Start-Process msiexec.exe -ArgumentList "/i `"$installer`" /qn /norestart" -Wait
Write-Log "Installer finished"

# 4. Verify
$verify = (Get-WmiObject -Class Win32_Product |
    Where-Object { $_.Name -like '*Apache*' } |
    Select-Object -First 1 -ExpandProperty Version)
if ([version]$verify -ge [version]'<patched-version>') {
    Write-Log "SUCCESS: now at $verify (>= <patched-version>)"
} else {
    Write-Log "FAILURE: still at $verify after install"
    exit 1
}

Bash script (Linux) - detect, back up, upgrade, verify, log


# Vendor advisory: https://github.com/JoakimBulow/
#!/usr/bin/env bash
set -euo pipefail
LOG=/var/log/apache-pdfbox-examples-patch-cve-2026-23907.log
log()  { echo "$(date -Iseconds)  $*" | tee -a "$LOG"; }

log "Starting CVE-2026-23907 remediation for Apache Software Foundation Apache PDFBox Examples"

# 1. Detect installed version (works for deb and rpm packages)
if command -v dpkg >/dev/null && dpkg -s apache-pdfbox-examples >/dev/null 2>&1; then
    CURRENT=$(dpkg-query -W -f='${Version}' apache-pdfbox-examples)
    PKG_MGR=apt
elif command -v rpm >/dev/null && rpm -q apache-pdfbox-examples >/dev/null 2>&1; then
    CURRENT=$(rpm -q --queryformat '%{VERSION}' apache-pdfbox-examples)
    PKG_MGR=dnf
else
    log "apache-pdfbox-examples not installed via apt or rpm; check your package manager or vendor instructions."
    exit 0
fi
log "Detected: apache-pdfbox-examples=$CURRENT (manager=$PKG_MGR)"

# 2. Backup config
BACKUP=/var/backups/apache-pdfbox-examples-$(date +%Y%m%d-%H%M)
mkdir -p "$BACKUP"
for d in /etc/apache-pdfbox-examples /etc/${pkg%%-*} ; do
    [ -d "$d" ] && cp -a "$d" "$BACKUP/" && log "Backed up $d to $BACKUP"
done

# 3. Upgrade
if [ "$PKG_MGR" = apt ]; then
    sudo apt-get update -y
    sudo apt-get install --only-upgrade -y apache-pdfbox-examples
else
    sudo dnf upgrade --security -y apache-pdfbox-examples
fi

# 4. Verify
if [ "$PKG_MGR" = apt ]; then
    NEW=$(dpkg-query -W -f='${Version}' apache-pdfbox-examples)
else
    NEW=$(rpm -q --queryformat '%{VERSION}' apache-pdfbox-examples)
fi
log "After upgrade: $NEW"

# Optionally compare against <patched-version> with dpkg --compare-versions or sort -V
log "Done. Restart the affected service if the package install did not."

If you can't patch immediately

These are runnable hardening commands. They reduce blast radius but they're not a replacement for the vendor patch.

Reject `../` and encoded variants at the reverse proxy

nginx:


location / {
    if ($request_uri ~* "(\.\./|%2e%2e/|%2e%2e%2f|%2f%2e%2e)") { return 403; }
    proxy_pass http://backend;
}

Apache mod_rewrite:


RewriteEngine On
RewriteCond %{REQUEST_URI} (\.\./|%2e%2e/|%2f%2e%2e) [NC]
RewriteRule .* - [F]

How to verify the fix worked

Run the version probe again and confirm the running build matches the Fixed in row above.


apache2 -v   # Debian/Ubuntu
httpd -v     # RHEL/CentOS

Expected output: the Server version line should show the patched build.

Then re-run any vulnerability scanner you used previously and confirm the finding for CVE-2026-23907 has cleared. Sweep your logs for the indicators of compromise listed in the vendor or CISA advisory, especially if the system was internet-reachable during the disclosure window.

Frequently asked questions

Is CVE-2026-23907 being actively exploited?