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CVE-2026-64613

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

Medium6.2EPSS 0.18%
Published
Updated
Reserved
Assigned by
CPANSec

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.

Timeline

  1. ID reserved

    By CPANSec

  2. · 1 day later

    Published

  3. · 2 days later

    Record updated

Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.

Scores

CVSS scores of CVE-2026-64613, by who scored it
Scored byCVSSScoreVector
CISA-ADPADP (enrichment)3.1Medium6.2CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
NVDNVD · Deferred3.1Medium6.2CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
EPSS (exploitation in 30 days)
0.18% · top 93% of all CVEs (7 Nov 2026)
CISA SSVC
Exploitation: none · Automatable: no · Technical impact: partial
Loading the EPSS history…

The list uses the assigner's score when there is one, then CISA's, then NVD's: Medium 6.2.

Weakness

Affected products

What to do

Solution: Upgrade to Data::Buffer::Shared 0.05 or later, which creates the backing file mode 0600 (owner-only) with O_NOFOLLOW.

Workaround: For deployments that cannot upgrade to 0.05, set a restrictive umask so the backing file is not world-readable and place it in a directory only the owning user can access.

References (2)

Sources

The same CVE in the primary databases and aggregators, to check against.

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Record last updated .