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FedoraOperating system · Fedoraproject

CVE-2022-23959

CRITICAL · 9.1 CVSS v3.1 Published 2022-01-26
Fix available
A fix is available. Upgrade to 4.1.11r6 / 6.0.9r4 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
In Varnish Cache before 6.6.2 and 7.x before 7.0.2, Varnish Cache 6.0 LTS before 6.0.10, and and Varnish Enterprise (Cache Plus) 4.1.x before 4.1.11r6 and 6.0.x before 6.0.9r4, request smuggling can occur for HTTP/1 connections.

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

A request smuggling vulnerability in Varnish Cache allows attackers to manipulate HTTP/1 request parsing, potentially causing the front-end and back-end servers to interpret requests differently. This can lead to cache poisoning, session hijacking, or bypassing security controls.

MitigationUpgrade Varnish Cache to version 6.6.2, 7.0.2, or 6.0.10 (or the corresponding Enterprise versions 4.1.11r6/6.0.9r4) to resolve the HTTP/1 request smuggling issue.

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:= 35
Debian LinuxOperating system
Affected:= 9.0= 10.0= 11.0
Varnich CacheApplication
Affected:>= 1.0.0, < 6.6.2>= 4.1.1, < 4.1.11r6= 4.1
Varnish CacheApplication
Affected:>= 6.0.0, < 6.0.10
Varnish Cache PlusApplication
Affected:>= 6.0.0, < 6.0.9r4
Varnish CacheApplication
Affected:>= 7.0.0, < 7.0.2

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
None

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

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. Determine installed Varnish version
    Run `varnishd -V` or `varnishd --version` to see the exact version number
    Affected if The version falls within any of these ranges: <6.6.2 (for 6.x), <4.1.11r6 (for 4.1.x), <6.0.10 (for 6.0.x), <7.0.2 (for 7.x), or is 4.1 (any update level)
  2. Check Varnish service status
    Run `systemctl status varnish` or `service varnish status` to confirm if Varnish is actively running
    Affected if Varnish is running and serving HTTP traffic (the vulnerability requires an active Varnish instance to be exploitable)
  3. Verify package version on Fedora
    Run `rpm -qa | grep varnish` to list installed Varnish packages
    Affected if Any varnish package is installed on Fedora 35 (which ships vulnerable Varnish versions)
  4. Verify package version on Debian
    Run `dpkg -l | grep varnish` to list installed Varnish packages
    Affected if Any varnish package is installed on Debian 9, 10, or 11 (which ship vulnerable Varnish versions)

You are affected if Varnish Cache is installed and the version is less than 6.6.2, 4.1.11r6, 6.0.10, or 7.0.2 (or is exactly version 4.1), regardless of whether it is the open source or Plus edition.

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 4.1.11r6 / 6.0.9r4 / 6.0.10 or later
Fixed in 4.1.11r66.0.9r46.0.10
Interim mitigation

Upgrade Varnish Cache to version 6.6.2, 7.0.2, or 6.0.10 (or the corresponding Enterprise versions 4.1.11r6/6.0.9r4) to resolve the HTTP/1 request smuggling issue.

Recommended fix High confidence

Varnish Cache 6.0.x -> 6.0.10; Varnish Cache 6.x -> 6.6.2; Varnish Cache 7.x -> 7.0.2; Varnish Cache Plus 4.1.x -> 4.1.11r6; Varnish Cache Plus 6.0.x -> 6.0.9r4

  1. 1. Identify the currently installed Varnish version using: varnishd -V
  2. 2. Determine the appropriate upgrade path based on your current version (6.0.x -> 6.0.10, 6.x -> 6.6.2, 7.x -> 7.0.2, or Enterprise variants to their respective patched releases)
  3. 3. For Fedora systems: Run 'sudo dnf update varnish' to upgrade to the patched version available in Fedora 35 repositories
  4. 4. For Debian systems: Run 'sudo apt update && sudo apt install varnish' to upgrade to the patched version available in Debian repositories
  5. 5. For Varnish Cache Plus (Enterprise): Contact Varnish Software for the patched packages (4.1.11r6 or 6.0.9r4)
  6. 6. After upgrading, restart the Varnish service using: sudo systemctl restart varnish
  7. 7. Verify the new version is running: varnishd -V
Caveat Configuration compatibility should be maintained when upgrading within the same major version (e.g., 6.0.x to 6.0.10); however, upgrading to 7.x may require configuration review for deprecated features

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

Fix this in Fedora Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
18.0 hours of engineering $3,040
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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-2022-23959 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