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Traffic ServerApplication · Apache

CVE-2019-9518

HIGH · 7.5 CVSS v3.1 Published 2019-08-13
Fix available
A fix is available. Upgrade to after 8.0.3 or later.
See remediation →
84/100
Remediation priority · High
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
Some HTTP/2 implementations are vulnerable to a flood of empty frames, potentially leading to a denial of service. The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA, HEADERS, CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU.

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

HTTP/2 implementations are vulnerable to a denial-of-service attack via floods of empty frames (DATA, HEADERS, CONTINUATION, PUSH_PROMISE) sent without the end-of-stream flag. The peer expends CPU processing each frame disproportionately to the attacker's bandwidth cost, leading to resource exhaustion.

MitigationImplement frame validation and rate limiting on HTTP/2 servers to reject or throttle empty frames that lack the end-of-stream flag, and monitor for anomalous patterns of frame volume.

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
Traffic ServerApplication
Affected:>= 6.0.0, <= 6.2.3>= 7.0.0, <= 7.1.6>= 8.0.0, <= 8.0.3
Ubuntu LinuxOperating system
Affected:= 16.04= 18.04= 19.04
Debian LinuxOperating system
Affected:= 9.0= 10.0
FedoraOperating system
Affected:= 29= 30
Jboss Core ServicesApplication
Affected:= 1.0
Jboss Enterprise Application PlatformApplication
Affected:= 7.2.0= 7.3.0
Openshift Service MeshApplication
Affected:= 1.0
QuayApplication
Affected:= 3.0.0

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Identify the HTTP/2 server or product in use
    Check running processes or installed packages. For Apache Traffic Server, run 'traffic_server -V' or check the package manager. For Linux distributions, identify the web server (Apache httpd, nginx) with 'httpd -v' or 'nginx -v'.
    Affected if The system is running Apache Traffic Server, or a Linux distribution from the affected list with an HTTP/2-enabled web server.
  2. Determine the exact version of Apache Traffic Server
    Run 'traffic_server -V' or check the installed package version via the package manager (dpkg -r or rpm -qi).
    Affected if The version falls within 6.0.0-6.2.3, 7.0.0-7.1.6, or 8.0.0-8.0.3.
  3. Check if HTTP/2 is enabled in the server configuration
    For Apache Traffic Server, examine records.yaml or remap.config for 'http2' settings. For Apache httpd, check for 'Protocols h2 http/1.1' in the configuration files. For nginx, check for 'listen ... http2' in server block configurations.
    Affected if HTTP/2 protocol support is explicitly enabled in the server configuration.
  4. Verify the Linux distribution version if running a packaged server
    Run 'cat /etc/os-release' or 'lsb_release -a' to identify the Ubuntu, Debian, Fedora, or RHEL version.
    Affected if The distribution matches Ubuntu 16.04, 18.04, 19.04, Debian 9.0 or 10.0, or Fedora 29 or 30, AND an HTTP/2-enabled web server is installed.
  5. Inspect HTTP/2 frame handling configuration
    Review the server configuration for any existing frame validation or rate limiting settings. For Apache Traffic Server, check the records.yaml for 'proxy.config.http2' related settings. Look for settings that control max empty frames, frame size limits, or rate limiting.
    Affected if No frame validation or rate limiting is configured for HTTP/2 empty frames, or default vulnerable behavior is in effect.

A system is affected if it runs any of the listed product versions with HTTP/2 protocol enabled and lacks specific frame validation or rate-limiting controls for empty frames.

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.

From vendor data
Upgrade available Upgrade to a release after 8.0.3
Interim mitigation

Implement frame validation and rate limiting on HTTP/2 servers to reject or throttle empty frames that lack the end-of-stream flag, and monitor for anomalous patterns of frame volume.

Fix this in Traffic Server Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
14.0 hours of engineering $2,490
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,984.

Scan for this in your stack

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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-2019-9518 in production — separate from our analysis above.

No notes yet

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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