Data::Buffer::Shared versions before 0.05 for Perl create a world-readable mmap backing file and open it without O_NOFOLLOW

published 2026-07-21 3 mo ago modified 2026-10-24 15 d ago also EUVD-2026-46369

cvss: 6.2; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 0.2%; EPSS 0.2% chance of exploitation in 30 days, percentile 7%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

EGOR Data::Buffer::Shared 0.05

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 3 mo ago (2026-07-23)

Exploit prediction

0.18% chance of exploitation in the next 30 days, higher than 7% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CISA ADP	3.1	6.2	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
CNA	3.1	6.2	CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Affected products

EGOR Data::Buffer::Shared

Classification

Weakness

CWE-732 Incorrect Permission Assignment for Critical Resource
CWE-59 Improper Link Resolution Before File Access

References

Sources

CVE List CVE-2026-64613
NVD CVE-2026-64613

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary