VulnerabilityPublished 25 Sep 2026Updated 19 Oct 2026

CVE-2026-97923: Linux kernel · tracing: Free histogram the var ref when its initialization fails

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in a69baeac38677270656e85753d93856a076dee57 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Low

Rated Low by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 11% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in a69baeac38677270656e85753d93856a076dee57, 4924328d6991f25b65bb7c8ff5d56c2a9b254851, 516001d53e6b2ea95a251ee2ef54a1a689a3fd58 +6

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Sep 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.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=4.19.100 <4.20	Fixed in a69baeac38677270656e85753d93856a076dee57 4924328d6991f25b65bb7c8ff5d56c2a9b254851 516001d53e6b2ea95a251ee2ef54a1a689a3fd58 74375caa20fe5165807b4334c783d1790b01f02a 4870f9071c9ea3c1423a07741b85a794db30d672 608b7751926ec08fae6a1ac4e7308195da68c362 352f84a381e7b4651b30366e93cb858f3fa9c91a 222abcbe7866fef04563b6eb89fb21f627dcbc77 4.20
LinuxLinux	Affected =5.0	Fixed in–

AI-suggested

The vulnerability has been fixed in Linux kernel versions 4.20 and later. Users should upgrade to version 4.20 or later to remediate this issue. No additional mitigation is required once the system is updated.

Description

A memory leak vulnerability in the Linux kernel tracing subsystem was fixed. The issue occurs when create_var_ref() allocates a VAR_REF hist_field and init_var_ref() fails to initialize it. Due to changes in how var_refs are freed, the allocated field is not freed on failure, causing a memory leak. The fix involves calling __destroy_hist_field() to properly free the field in failure cases.

Impact

This vulnerability causes a memory leak in the Linux kernel tracing subsystem when initialization of a histogram variable reference fails. While it does not directly lead to code execution or privilege escalation, memory leaks can degrade system stability and performance over time, especially in long-running systems or those heavily using tracing features.

Summary

In the Linux kernel tracing code, create_var_ref() allocates a VAR_REF hist_field and calls init_var_ref() to initialize it. If init_var_ref() fails, the allocated field is leaked because it is not added to the var_refs array and destroy_hist_field() returns early for HIST_FIELD_FL_VAR_REF fields, relying on the var_refs array to free them. init_var_ref() does not free the field itself to avoid use-after-free issues. The fix calls __destroy_hist_field() directly to free the field without consulting flags, preventing the memory leak.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 13:24 UTC

Technical details

References

Community reviews

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