CPANSA-Data-Buffer-Shared-2026-64613: Data-Buffer-Shared vulnerability
| Publisher | giterlizzi | Document category | csaf_security_advisory |
|---|---|---|---|
| Initial release date | 2026-07-21T00:00:00 | Engine | CSAF Perl Toolkit 0.26 |
| Current release date | 2026-07-21T00:00:00 | Build Date | |
| Current version | 1 | Status | final |
| CVSS v3.1 Base Score | 6.2 | Severity | Medium |
| Original language | Language | en | |
| Also referred to | |||
Vulnerability 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.
Vulnerabilities
CVE-2026-64613
Vulnerability DescriptionData::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.
| Weakness | CWE-59 : Improper Link Resolution Before File Access ('Link Following') |
|---|
Product status
Known affected
| Product | Score | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Data-Buffer-Shared less than 0.05 |
|
Fixed
- Data-Buffer-Shared greater than or equal 0.05
giterlizzi
Namespace: https://github.com/giterlizzi/
gdt@cpan.org
References
- CPANSA-Data-Buffer-Shared-2026-64613 JSON self
https://raw.githubusercontent.com/giterlizzi/perl-CPANSA-CSAF/develop/csaf/white/2026/cpansa-data-buffer-shared-2026-64613.json - https://metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/changes external
https://metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/changes - https://metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/diff/EGOR/Data-Buffer-Shared-0.04#buf_generic.h external
https://metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/diff/EGOR/Data-Buffer-Shared-0.04#buf_generic.h - CVE-2026-64613 (NVD) external
https://nvd.nist.gov/vuln/detail/CVE-2026-64613
Revision history
| Version | Date of the revision | Summary of the revision |
|---|---|---|
| 1 | Tue Jul 21 00:00:00 2026 | First release |
Sharing rules
TLP:WHITE
For the TLP version see: https://www.first.org/tlp/