CVE-2026-65064: Data::HashMap::Shared versions before 0.14 for Perl create a world-readable mmap backing file and open it without O_EXCL or O_NOFOLLOW

Severity: low (CVSS 3.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-21 · updated 2026-10-24
Weakness: CWE-59

Description

Data::HashMap::Shared versions before 0.14 for Perl create a world-readable mmap backing file and open it without O_EXCL or O_NOFOLLOW. The segment is created in shm_generic.h with open(path, O_RDWR | O_CREAT | O_CLOEXEC, 0666). The mode is 0666, so under the default umask 022 the file is created mode 0644 (world-readable). O_NOFOLLOW is absent, so a symlink planted at the path is followed, and O_EXCL is absent, so the open silently uses a pre-planted file instead of failing. 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 file or symlink at the path lets a local attacker win a pre-creation race or redirect the open.

Affected products

EGOR Data::HashMap::Shared: before 0.14 — fixed in 0.14

How to fix

Upgrade to a fixed version: EGOR Data::HashMap::Shared 0.14. Check the vendor advisory for mitigations.

References

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