CVE-2026-12087: Socket versions before 2.041 for Perl have an out-of-bounds heap read

[Robert Rothenberg <rrwo () cpansec org>]

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CVE-2026-12087                                       CPAN Security Group
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        CVE ID:  CVE-2026-12087
  Distribution:  Socket
      Versions:  before 2.041

      MetaCPAN:  https://metacpan.org/dist/Socket


Socket versions before 2.041 for Perl have an out-of-bounds heap read

Description
-----------
Socket versions before 2.041 for Perl have an out-of-bounds heap read.

In Socket.xs, pack_ip_mreq_source() checks the length of its source
argument before the argument is read, so the check tests the byte
length carried over from the preceding multiaddr argument instead. Both
addresses occupy a 4-byte field, so a valid multiaddr lets a source of
any length pass the check, and the source is then copied into the
4-byte imr_sourceaddr field with a fixed-size copy. A source shorter
than 4 bytes is not rejected, and the copy reads up to 3 bytes past the
end of its buffer.

Calling pack_ip_mreq_source() with a source value shorter than 4 bytes
copies adjacent heap memory into the returned packed structure.

Problem types
-------------
- CWE-125 Out-of-bounds Read
- CWE-805 Buffer Access with Incorrect Length Value

Solutions
---------
Upgrade to version 2.041 or later.


References
----------
https://metacpan.org/release/PEVANS/Socket-2.041/changes
https://github.com/Perl/perl5/commit/de19a0b0ad1900fef976c5c1400bd8f11ec6c6cb.patch