dbcve.org
FedoraOperating system · Fedoraproject

CVE-2019-16239

CRITICAL · 9.8 CVSS v3.1 Published 2019-09-17
Fix available
A fix is available. Upgrade to 8.05 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
process_http_response in OpenConnect before 8.05 has a Buffer Overflow when a malicious server uses HTTP chunked encoding with crafted chunk sizes.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

OpenConnect VPN client before version 8.05 contains a buffer overflow vulnerability in the process_http_response function. When the client connects to a malicious VPN server that sends HTTP responses using chunked transfer encoding with specially crafted chunk sizes, the buffer overflow occurs, potentially allowing remote code execution on the client machine.

MitigationUpgrade OpenConnect client to version 8.05 or later which contains the fix for proper bounds checking on HTTP chunked encoding parsing.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
FedoraOperating system
Affected:= 29= 30= 31
Debian LinuxOperating system
Affected:= 8.0= 9.0= 10.0
Ubuntu LinuxOperating system
Affected:= 18.04
OpenconnectApplication
Affected:< 8.05
LeapOperating system
Affected:= 15.0= 15.1

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check if OpenConnect is installed
    Run 'openconnect --version' or check your package manager (dpkg -l | grep openconnect or rpm -qa | grep openconnect)
    Affected if OpenConnect is installed and the version is less than 8.05
  2. Identify the exact OpenConnect version
    Execute 'openconnect --version' and note the version number in the output (format typically shows like openconnect version X.XX)
    Affected if The version number displayed is below 8.05 (for example 8.04, 8.02, etc.)
  3. Confirm the vulnerable binary exists
    Locate the openconnect binary with 'which openconnect' or 'find /usr -name openconnect -type f'
    Affected if The binary exists and corresponds to a version below 8.05 when checked with --version
  4. Check if the client is configured for VPN connections
    Review any OpenConnect configuration files in /etc/openconnect/ or ~/.config/openconnect/ or check for any saved VPN profiles
    Affected if OpenConnect client configurations exist, indicating regular use of the client to connect to VPN servers

You are affected if OpenConnect client version is installed and is lower than 8.05, as the buffer overflow in process_http_response triggers when connecting to a malicious VPN server using chunked transfer encoding.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 8.05 or later
Fixed in 8.05
Interim mitigation

Upgrade OpenConnect client to version 8.05 or later which contains the fix for proper bounds checking on HTTP chunked encoding parsing.

Recommended fix High confidence

OpenConnect 8.05 or later

  1. For Fedora systems: Run 'sudo dnf update openconnect' to update to the latest version containing the fix
  2. For Debian systems: Run 'sudo apt-get update && sudo apt-get install openconnect' to install version 8.05 or later
  3. For Ubuntu systems: Run 'sudo apt-get update && sudo apt-get install openconnect' to get the patched version
  4. For openSUSE Leap: Run 'sudo zypper update openconnect' to upgrade to the fixed version
  5. Verify the installed version with 'openconnect --version' and confirm it shows version 8.05 or later
  6. Alternatively, download OpenConnect 8.05 or later from the official source and compile/install manually if packages are not available
Caveat Upgrading OpenConnect may require updating dependent packages; ensure VPN client compatibility with your organization's VPN server before upgrading in production environments

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Fedora Scoped from the published advisory
  • Consultation1.0 h
  • Implementation1.0 h
  • Testing2.0 h
  • Review / QA1.0 h
5.0 hours of engineering $860
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,376.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2019-16239 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-16239 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data