[CVE-2025-54574] SQUID-2025:1 Buffer Overflow in URN Handling

[Amos Jeffries <squid3 () treenet co nz>]

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     Squid Proxy Cache Security Update Advisory SQUID-2025:1
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Advisory ID:       | SQUID-2025:1, CVE-2025-54574
Date:              | August 1, 2025
Summary:           | Buffer Overflow in URN Handling
Affected versions: | Squid 2.x -> 2.7.STABLE9
                   | Squid 3.x -> 3.5.28
                   | Squid 4.x -> 4.17
                   | Squid 5.x -> 5.9
                   | Squid 6.x -> 6.3
Fixed in version:  | Squid 6.4
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Problem Description:

  Due to incorrect buffer management Squid is vulnerable to a
  heap buffer overflow and possible remote code execution attack
  when processing URN.

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Severity:

  This problem allows a remote server to perform a Buffer Overflow
  attack when delivering URN Trivial-HTTP responses. Potentially
  allowing delivery of up to 4KB of Squid allocated heap memory
  to the client.

  Revealed memory may include security credentials or other
  confidential data.

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Updated Packages:

  This bug is fixed by Squid version 6.4.

  In addition, patches addressing this problem for the stable
  releases can be found in our patch archives:

  Squid 6:
 
<https://github.com/squid-cache/squid/commit/a27bf4b84da23594150c7a86a23435df0b35b988>

  If you are using a prepackaged version of Squid then please refer
  to the package vendor for availability information on updated
  packages.

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Determining if your version is vulnerable:

  Squid older than 4.14 have not been tested and should be assumed
  to be vulnerable.

  All Squid-4.x up to and including 4.17 are vulnerable.

  All Squid-5.x up to and including 5.9 are vulnerable.

  All Squid-6.x up to and including 6.3 are vulnerable.

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Workaround:

  Disable URN access permissions.

   acl URN proto URN
   http_access deny URN

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Contact details for the Squid project:

  For installation / upgrade support on binary packaged versions
  of Squid: Your first point of contact should be your binary
  package vendor.

  If you install and build Squid from the original Squid sources
  then the <squid-users at lists.squid-cache.org> mailing list is your
  primary support point. For subscription details see
  <http://www.squid-cache.org/Support/mailing-lists.html>.

  For reporting of non-security bugs in the latest STABLE release
  the squid bugzilla database should be used
  <https://bugs.squid-cache.org/>.

  For reporting of security sensitive bugs send an email to the
  <squid-bugs at lists.squid-cache.org> mailing list. It's a closed
  list (though anyone can post) and security related bug reports
  are treated in confidence until the impact has been established.

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Credits:

  This vulnerability was discovered by StarryNight.

  Fixed by The Measurement Factory.

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Revision history:
  2023-06-24 08:18:55 UTC Fix published
  2025-07-01 18:40:24 UTC Initial Report
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