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

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Summary

CVECVE-2026-64613
StatePUBLISHED
AssignerCPANSec
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-07-21 20:17:03 UTC
Updated2026-07-21 20:17:03 UTC
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.

Risk And Classification

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA EGOR DataBufferShared affected 0.05 custom Not specified

References

ReferenceSourceLinkTags
metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/changes 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
metacpan.org/release/EGOR/Data-Buffer-Shared-0.05/diff/EGOR/Data-Buffer-Sh... 9b29abf9-4ab0-4765-b253-1875cd9b441e metacpan.org
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

Solutions

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

Workarounds

CNA: 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.

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