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NVD / CVE Program· CNA Linux

CVE-2026-74636: tracing: Fix race between update_event_fields and, event_define_fields

Noroxi assessment

Priority: Monitor (action score 0/100)

  • The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
  • Probability of exploitation in the next 30 days: 0.17% (FIRST EPSS).
  • Fixed version: Linux Linux 4e39f7b4d9d36508c53e89e6cbc640728df870b5, 5.15.216, 5.17; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 4e39f7b4d9d36508c53e89e6cbc640728df870b5, 5.15.216, 5.17; azl3 kernel 6.6.150.1-1 on Azure Linux 3.0 6.6.152.1-1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

—No exploit Fix available
Published
Aug 22, 2026
Updated
Nov 6, 2026
EPSS
0.1% · 6th percentile
CWE
—

Report tools

JSON

Action score

0

Monitor

Low priority for now.

CVSS
0 / 40 · —
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

CISA SSVC decision

Exploitation
none
Automatable
no
Technical impact
partial

Vulnrichment: CISA's decision-tree inputs.

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Noroxi analysis

What does it mean in your environment?

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (Linux). Independent of NVD's CPE analysis and usually ahead of it.

  • Linux Linux

    • 55defdf935fab9f2989a197aae1042c082d9a343, 0c53a5c80e6e286733381a1d9f255ba4039e2e45, 5.18affected
    • 7c6bd60999f32138e3b73fd97ea11ef47a94de25 and later · before 4e39f7b4d9d36508c53e89e6cbc640728df870b5affected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before a30d421468300b1e7b2f233136aeb2db8013f555affected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before e5f1d301b4bdaa4206db251fdc691f623162b0a8affected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before fdeb190b0905a6aaed1e5d6adfb8613214748d7daffected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before ed49684e69f846bf50b5050651ccdb87cfd152c0affected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before f128740f39ab28d1f4ad5bdd10f3e117eec0c374affected · git
    • b3bc8547d3be60898818885f5bf22d0a62e2eb48 and later · before c3730b8373bb5059d735509b9e6a00d7eb337d7caffected · git
    • 5.15.33 and later · before 5.15.216affected · semver
    • 5.16.19 and later · before 5.17affected · semver

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.187-16.1.187-1
Debian:12linux-6.12before 6.12.107-1~deb12u16.12.107-1~deb12u1
Debian:13linuxbefore 6.12.105-16.12.105-1
Debian:14linuxbefore 7.1.9-17.1.9-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-74705udp: fix potential use-after-free in tunnel segmentation
    40Plan
  • CVE-2026-74612veth: fix skb length accounting after XDP frag adjustment
    40Plan
  • CVE-2026-74475vxlan: use neigh_ha_snapshot() in route_shortcircuit()
    40Plan

Published before and after this one in the same product

  • ← EarlierCVE-2026-74634Aug 22, 2026 · ring-buffer: Prevent subbuf order change when resizing is disabled
    31Monitor
  • ← EarlierCVE-2026-74635Aug 22, 2026 · fbdev: bitblit: bound-check glyph index in bit_cursor()
    31Monitor
  • Later →CVE-2026-74637Aug 22, 2026 · perf/core: Fix group leader use-after-free after sibling detach
    31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Linux Linux4e39f7b4d9d36508c53e89e6cbc640728df870b5Vendor (CNA)
Linux Linux5.15.216Vendor (CNA)
Linux Linux5.17Vendor (CNA)
Linux Linux5.18Vendor (CNA)
Linux Linuxa30d421468300b1e7b2f233136aeb2db8013f555Vendor (CNA)
Linux Linuxc3730b8373bb5059d735509b9e6a00d7eb337d7cVendor (CNA)
Linux Linuxe5f1d301b4bdaa4206db251fdc691f623162b0a8Vendor (CNA)
Linux Linuxed49684e69f846bf50b5050651ccdb87cfd152c0Vendor (CNA)
Linux Linuxf128740f39ab28d1f4ad5bdd10f3e117eec0c374Vendor (CNA)
Linux Linuxfdeb190b0905a6aaed1e5d6adfb8613214748d7dVendor (CNA)
azl3 kernel 6.6.150.1-1 on Azure Linux 3.06.6.152.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.187-1 · Debian:12Package registry (OSV)
debian:linux-6.126.12.107-1~deb12u1 · Debian:12Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

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Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

All national notices →

Technical details

No CVSS vector for this record, so attack conditions can't be derived.

Weakness class (CWE)

—

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

MITRE has no CAPEC/ATT&CK mapping for this CWE.

Change log

  1. SSVC exploitation— → none
  2. Fix✗ → ✓

For records you follow, these changes also arrive as notifications. →

References

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records