CVE-2026-74636: Linux kernel · tracing: Fix race between update_event_fields and, event_define_fields
Affects Linux kernelSource GCVE Database
Not known to be exploited · fixed in 5.15.0-1117.124~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 12:55 UTC
Rated by Threat Radar · CVSS not yet scored by NVD
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 6% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1117.124~20.04.1, 5.15.0-1123.132~20.04.1, 5.15.0-1122.131~20.04.1 +26
Exploitation evidence
Disclosed: evidence found.
CVE published 22 Aug 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available that fixes the race condition by adding proper locking in the trace_event_update_all() function. Users should apply the official kernel updates for the affected versions to remediate this issue.
Description
A race condition vulnerability in the Linux kernel tracing subsystem was resolved. The flaw involved a race between event_define_fields() and update_event_fields() functions, leading to a kernel panic due to unprotected access to class->fields. This could cause system instability or crashes. The issue affects specific Linux kernel versions and has been fixed by ensuring proper locking with event_mutex in trace_event_update_all().
References
- nvd.nist.gov/vuln/detail/CVE-2026-74636 (opens in a new tab)
- git.kernel.org/stable/c/4e39f7b4d9d36508c53e89e6cbc640728df870b5 (opens in a new tab)
- git.kernel.org/stable/c/a30d421468300b1e7b2f233136aeb2db8013f555 (opens in a new tab)
- git.kernel.org/stable/c/c3730b8373bb5059d735509b9e6a00d7eb337d7c (opens in a new tab)
- git.kernel.org/stable/c/e5f1d301b4bdaa4206db251fdc691f623162b0a8 (opens in a new tab)
- git.kernel.org/stable/c/ed49684e69f846bf50b5050651ccdb87cfd152c0 (opens in a new tab)
- git.kernel.org/stable/c/f128740f39ab28d1f4ad5bdd10f3e117eec0c374 (opens in a new tab)
- git.kernel.org/stable/c/fdeb190b0905a6aaed1e5d6adfb8613214748d7d (opens in a new tab)
- ubuntu.com/security/CVE-2026-74636 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-74636 (opens in a new tab)
- git.kernel.org/linus/c3730b8373bb5059d735509b9e6a00d7eb337d7c (opens in a new tab)
- ubuntu.com/security/notices/USN-8878-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8879-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8877-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8875-2 (opens in a new tab)