Data::Buffer::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_NOFOLLOW. The segment is created in buf_generic.h with open(path, O_RDWR|O_CREAT|O_EXCL, 0666). O_EXCL blocks a pre-seeded file on create, but the mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable), and O_NOFOLLOW is absent, so a symlink planted at the path is followed when the segment is attached. A "Shared" segment naturally lives in a shared directory such as /tmp or /dev/shm, where any local user can read the IPC payloads stored in the world-readable segment, and a pre-planted symlink at the path redirects the open to another file.
History

Thu, 23 Jul 2026 21:45:00 +0000

Type Values Removed Values Added
First Time appeared Egor
Egor data::buffer::shared
Vendors & Products Egor
Egor data::buffer::shared

Thu, 23 Jul 2026 13:30:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 6.2, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Tue, 21 Jul 2026 19:45:00 +0000

Type Values Removed Values Added
Description Data::Buffer::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_NOFOLLOW. The segment is created in buf_generic.h with open(path, O_RDWR|O_CREAT|O_EXCL, 0666). O_EXCL blocks a pre-seeded file on create, but the mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable), and O_NOFOLLOW is absent, so a symlink planted at the path is followed when the segment is attached. A "Shared" segment naturally lives in a shared directory such as /tmp or /dev/shm, where any local user can read the IPC payloads stored in the world-readable segment, and a pre-planted symlink at the path redirects the open to another file.
Title Data::Buffer::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_NOFOLLOW
Weaknesses CWE-59
CWE-732
References

cve-icon MITRE

Status: PUBLISHED

Assigner: CPANSec

Published: 2026-07-21T19:05:49.579Z

Updated: 2026-07-23T12:25:36.375Z

Reserved: 2026-07-20T11:30:10.287Z

Link: CVE-2026-64613

cve-icon Vulnrichment

Updated: 2026-07-23T12:23:57.187Z

cve-icon NVD

No data.

cve-icon Redhat

No data.