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PatchSiren cyber security CVE debrief

CVE-2026-46089 Linux CVE debrief

A vulnerability in the Linux kernel's zram driver causes partial discard requests to hang indefinitely. The issue occurs because zram does not support partial discards and returns early without completing the I/O operation, leaving processes waiting in submit_bio_wait(). The fix ensures bio_endio() is called via the end_bio label before exiting.

Vendor
Linux
Product
Unknown
CVSS
Unknown
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-27
Original CVE updated
2026-05-27
Advisory published
2026-05-27
Advisory updated
2026-05-27

Who should care

System administrators running Linux systems with zram enabled for swap or compressed block storage; kernel maintainers and distribution packagers; developers of storage management tools that issue discard operations.

Technical summary

The zram compressed RAM block device driver in the Linux kernel contains a bug where partial discard requests are not properly completed. When a discard operation with a partial block size (e.g., 4KB on a system with 64KB pages) is submitted to /dev/zram0, the driver recognizes it cannot process the partial discard and returns early. However, it fails to call bio_endio() to signal completion, causing the submitting process to sleep indefinitely in submit_bio_wait(). The fix redirects the early return path to the end_bio label to ensure proper I/O completion.

Defensive priority

medium

Recommended defensive actions

  • Apply kernel updates containing the referenced stable branch commits when available from your Linux distribution
  • Monitor NVD for CVSS scoring once analysis is complete
  • Review systems using zram for swap or compressed block storage
  • Test blkdiscard operations on zram devices after patching to verify resolution

Evidence notes

CVE published 2026-05-27. Linux kernel stable branch commits provided as references. No CVSS score assigned; NVD status is Awaiting Analysis. Not listed in CISA KEV.

Official resources

2026-05-27