CVE-2026-65066 EGOR CVE debrief

Who should care

Users of Data::RingBuffer::Shared versions before 0.04 for Perl, especially those with shared directories such as /tmp or /dev/shm, should be aware of the potential for local attackers to read IPC payloads or win a pre-creation race. Affected operators, platforms, and security teams should review the vulnerability and take necessary actions to mitigate the risk.

Technical summary

The Data::RingBuffer::Shared module for Perl creates a world-readable mmap backing file due to a missing O_EXCL and O_NOFOLLOW flags when opening the file. Specifically, the file is created with open(path, O_RDWR|O_CREAT, 0666), resulting in a file mode of 0644 (world-readable) under the default umask 022. This allows any local user to read the IPC payloads stored in the shared segment. Additionally, the absence of O_NOFOLLOW allows a symlink planted at the path to be followed, and the absence of O_EXCL allows the open to silently use a pre-planted file instead of failing.

Defensive priority

High

Recommended defensive actions

• Update to Data::RingBuffer::Shared version 0.04 or later
• Use O_EXCL and O_NOFOLLOW flags when opening the mmap backing file
• Restrict access to shared directories such as /tmp or /dev/shm
• Monitor for suspicious activity in shared directories
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

The CVE record was published on 2026-07-21T20:17:05.637Z and has not been modified since then. The NVD entry is currently Deferred. There is limited information available about the vulnerability, and defenders should verify the affected scope and severity with the vendor. The Data::RingBuffer::Shared module for Perl creates a world-readable mmap backing file due to a missing O_EXCL and O_NOFOLLOW flags when opening the file.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.