tracing: Fix race between update_event_fields and, event_define_fields
Key facts
- Attack vector
- —
- Privileges required
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- User interaction
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- Attack complexity
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- Impact type
- —
- Confidentiality · integrity · availability
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- Fix status
- Partial Red Hat: 3 without a fix
No CVSS vector from any source. Fix status from CNA and Red Hat.
Summary
In the Linux kernel, the following vulnerability has been resolved: tracing: Fix race between update_event_fields and, event_define_fields The following sequence may leads race between event_define_fields() and update_event_fields(): CPU0 (loads module A) CPU1 (loads module B) =============================== =============================== load_module(A) load_module(B) notifier_call_chain notifier_call_chain trace_module_notify trace_module_notify mutex_lock(&event_mutex) trace_event_update_all() trace_module_add_events(A) down_write(&trace_event_sem) __register_event(call_A) __add_event_to_tracers(call_A) event_define_fields(call_A) for each f: list_for_each_entry(field, list_add(&f->link, &class->fields, link) &class->fields) field = class->fields->next; Where access to the class->fields is not protected by the event_mutex in trace_event_update_all(). This produces the following panic: Unable to handle kernel access ... at virtual address 0000000000000018 pc : update_event_fields+0xf8/0x368 Call trace: update_event_fields+0xf8/0x368 trace_event_update_all+0x7c/0x2b4 trace_module_notify+0x4c/0x1dc notifier_call_chain+0x84/0x168 blocking_notifier_call_chain_robust+0x64/0xd4 load_module+0x10c8/0x123c __arm64_sys_finit_module+0x230/0x31c Fix by taking event_mutex in trace_event_update_all() before trace_event_sem.
Why it matters now
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
Remediation
- Fix · CNA Linux (Linux) Fixed in 5.15.216, 5.17, 5.18
- Fix · CNA Linux (Linux) Fixed in 5.15.216, 6.1.183, 6.6.152, 6.12.104, 6.18.45, 7.1.9, 7.2
Vendor assessments
Red Hat
Red Hat rating: Low. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 10 | Affected | No fix yet: Fix deferred |
| Red Hat Enterprise Linux 6 | Affected | No fix planned: Out of support scope |
| Red Hat Enterprise Linux 9 | Affected | No fix yet: Fix deferred |
Not affected: 3 products
- Red Hat Enterprise Linux 7
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-74636
- 2026-10-03 Alias added: GHSA-jcq2-873m-mp53
- 2026-10-29 Affected versions changed · Red Hat
- 2026-11-06 CISA SSVC decision points changed
References
Other 7
- https://git.kernel.org/stable/c/4e39f7b4d9d36508c53e89e6cbc640728df870b5
- https://git.kernel.org/stable/c/a30d421468300b1e7b2f233136aeb2db8013f555
- https://git.kernel.org/stable/c/e5f1d301b4bdaa4206db251fdc691f623162b0a8
- https://git.kernel.org/stable/c/fdeb190b0905a6aaed1e5d6adfb8613214748d7d
- https://git.kernel.org/stable/c/ed49684e69f846bf50b5050651ccdb87cfd152c0
- https://git.kernel.org/stable/c/f128740f39ab28d1f4ad5bdd10f3e117eec0c374
- https://git.kernel.org/stable/c/c3730b8373bb5059d735509b9e6a00d7eb337d7c
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Sources
- CVE-2026-74636 · CVE Program
- CVE-2026-74636 · NVD
- FIRST EPSS
- GHSA-jcq2-873m-mp53 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-74636 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences