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Traffic ServerApplication · Apache

CVE-2019-9516

MEDIUM · 6.5 CVSS v3.1 Published 2019-08-13
Fix available
A fix is available. Upgrade to after 8.0.3 or later.
See remediation →
71/100
Remediation priority · Elevated
High EPSS Remotely reachable 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 header leak, potentially leading to a denial of service. The attacker sends a stream of headers with a 0-length header name and 0-length header value, optionally Huffman encoded into 1-byte or greater headers. Some implementations allocate memory for these headers and keep the allocation alive until the session dies. This can consume excess memory.

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 do not properly handle headers with zero-length names and values. Attackers can send streams of such empty headers (optionally Huffman encoded) causing the server to allocate memory that persists for the session lifetime, leading to memory exhaustion and denial of service.

MitigationUpdate HTTP/2 server implementations to a version that rejects or does not allocate memory for zero-length headers, and implement session-level memory limits for header storage.

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:= 30= 29= 32
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
Low
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/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 HTTP/2 enabled services
    Check running processes and listening services that handle HTTP/2 traffic. On Linux, use 'ss -tlnp' or 'netstat -tlnp' to list listening services, then review their configuration for HTTP/2 enablement (look for 'h2' or 'h2c' in TLS ALPN protocols or HTTP/2 protocol negotiation settings).
    Affected if HTTP/2 is enabled and the service is exposed to untrusted network traffic.
  2. Determine Apache Traffic Server version
    If Apache Traffic Server is in use, check the installed version by running 'traffic_server -V' or inspecting the package manager output (dpkg -r, rpm -qi).
    Affected if The version falls within 6.0.0 to 6.2.3, 7.0.0 to 7.1.6, or 8.0.0 to 8.0.3.
  3. Check Ubuntu, Debian, or Fedora OS-level HTTP/2 libraries
    Identify any HTTP/2 server packages or libraries installed at the OS level. On Ubuntu/Debian, check 'dpkg -l | grep -i http2' or review installed packages that provide HTTP/2 functionality. On Fedora, use 'rpm -qa'.
    Affected if The OS version matches 16.04, 18.04, 19.04 (Ubuntu), 9.0 or 10.0 (Debian), or 29, 30, 32 (Fedora) and runs HTTP/2 services.
  4. Identify Red Hat JBoss or related services
    If JBoss Core Services (1.0), JBoss Enterprise Application Platform (7.2.0 or 7.3.0), OpenShift Service Mesh (1.0), or Quay (3.0.0) are deployed, check the version using 'rpm -qi' for the respective packages or check the product version in the management console.
    Affected if The exact versions listed are running and HTTP/2 protocol handling is enabled.
  5. Verify HTTP/2 header processing configuration
    Review the HTTP/2 server configuration files for settings related to header handling. Check for any existing header size limits or memory constraints that may mitigate the zero-length header issue. Look for directives like 'max_header_fields', 'max_header_size', or equivalent in the server configuration.
    Affected if No header field count or size limits are configured, allowing unbounded memory allocation for headers.

Your environment is affected if any listed product version is running with HTTP/2 enabled and exposed to network traffic, with no header count or size limits configured.

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

Update HTTP/2 server implementations to a version that rejects or does not allocate memory for zero-length headers, and implement session-level memory limits for header storage.

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.

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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-2019-9516 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