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SquidApplication · Squid Cache

CVE-2023-50269

HIGH · 7.5 CVSS v3.1 Published 2023-12-14
Fix available
A fix is available. Upgrade to after 6.5 or later.
See remediation →
84/100
Remediation priority · High
High EPSS Remotely reachable No privileges Zero-click Patch available

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
Squid is a caching proxy for the Web. Due to an Uncontrolled Recursion bug in versions 2.6 through 2.7.STABLE9, versions 3.1 through 5.9, and versions 6.0.1 through 6.5, Squid may be vulnerable to a Denial of Service attack against HTTP Request parsing. This problem allows a remote client to perform Denial of Service attack by sending a large X-Forwarded-For header when the follow_x_forwarded_for feature is configured. This bug is fixed by Squid version 6.6. In addition, patches addressing this problem for the stable releases can be found in Squid's patch archives.

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

A detailed technical summary for this CVE is being prepared.

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
SquidApplication
Affected:>= 3.1, <= 5.9>= 6.0.1, <= 6.5= 2.6= 2.7

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

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 a release after 6.5
Vendor patch www.squid-cache.org →
Recommended fix High confidence

Squid 6.6 or later

  1. 1. Identify the currently installed Squid version using: squid -v or rpm -q squid / dpkg -l squid
  2. 2. Backup the existing Squid configuration directory (typically /etc/squid or /etc/squid3)
  3. 3. Upgrade to Squid version 6.6 or later using your system's package manager (e.g., apt-get install squid, yum update squid, or dnf update squid)
  4. 4. If your distribution does not yet have Squid 6.6 available, download the source from www.squid-cache.org and compile version 6.6 or later
  5. 5. Verify the new version is running: squid -v
  6. 6. Review the Squid configuration to ensure follow_x_forwarded_for settings are appropriate for your environment
  7. 7. Restart the Squid service: systemctl restart squid
Caveat Major version upgrades (e.g., Squid 2.x/3.x to 6.x) may introduce configuration syntax changes; review the Squid upgrade guide and test configuration with squid -k parse before restarting

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

We can identify the exact fixed release, upgrade, and verify it in staging — typical engagement from $1,950. Get the upgrade done

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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-2023-50269 in production — separate from our analysis above.

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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