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NVD / CVE Program· CNA Linux

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

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: 0.21% (FIRST EPSS).
  • Fixed version: Linux Linux 222abcbe7866fef04563b6eb89fb21f627dcbc77, 352f84a381e7b4651b30366e93cb858f3fa9c91a, 4.20; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1.
  • Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to Linux Linux 222abcbe7866fef04563b6eb89fb21f627dcbc77, 352f84a381e7b4651b30366e93cb858f3fa9c91a, 4.20; azl3 kernel 6.6.157.1-1 on Azure Linux 3.0 6.6.158.1-1 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: Free histogram the var ref when its initialization fails create_var_ref() allocates a VAR_REF hist_field and then calls init_var_ref() to fill it in. When that fails the field is leaked. commit 656fe2ba85e8 ("tracing: Use hist trigger's var_ref array to destroy var_refs") made destroy_hist_field() return early for HIST_FIELD_FL_VAR_REF, since var refs are freed by walking the trigger's var_refs[] array instead. create_var_ref() adds the field to that array only after init_var_ref() has succeeded, so on this path the field is in neither place and nothing frees it. The call was correct when it was written, before var refs were taken out of destroy_hist_field(). init_var_ref() cannot free it either. The caller owns the field, so init_var_ref() undoes only its own string allocations and leaves the field alone. Freeing it there would leave create_var_ref() passing freed memory to destroy_hist_field(), which reads its flags. Call __destroy_hist_field(), which frees the field without consulting the flag.

—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 19, 2026
EPSS
0.2% · 11th 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 · 0.2%

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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

    • 836717841a30d7845cdf9cb806ee0ff3bfa7135a, 5.0affected
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 608b7751926ec08fae6a1ac4e7308195da68c362affected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 4870f9071c9ea3c1423a07741b85a794db30d672affected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 352f84a381e7b4651b30366e93cb858f3fa9c91aaffected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 4924328d6991f25b65bb7c8ff5d56c2a9b254851affected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 74375caa20fe5165807b4334c783d1790b01f02aaffected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 222abcbe7866fef04563b6eb89fb21f627dcbc77affected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before a69baeac38677270656e85753d93856a076dee57affected · git
    • 656fe2ba85e81d00e4447bf77b8da2be3c47acb2 and later · before 516001d53e6b2ea95a251ee2ef54a1a689a3fd58affected · git
    • 4.19.100 and later · before 4.20affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.190-16.1.190-1
Debian:12linux-6.12before 6.12.111-1~deb12u16.12.111-1~deb12u1
Debian:13linuxbefore 6.12.111-16.12.111-1
Debian:14linuxbefore 7.2.7-17.2.7-1

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-2026-97921Sep 25, 2026 · tracing: Free histogram the field rejected for a bad modifier
    0Monitor
  • ← EarlierCVE-2026-97922Sep 25, 2026 · tracing: Free histogram var refs regardless of how often they are referenced
    0Monitor
  • Later →CVE-2026-97924Sep 25, 2026 · tracing/user_events: Don't destroy fields when event removal fails
    0Monitor

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 Linux222abcbe7866fef04563b6eb89fb21f627dcbc77Vendor (CNA)
Linux Linux352f84a381e7b4651b30366e93cb858f3fa9c91aVendor (CNA)
Linux Linux4.20Vendor (CNA)
Linux Linux4870f9071c9ea3c1423a07741b85a794db30d672Vendor (CNA)
Linux Linux4924328d6991f25b65bb7c8ff5d56c2a9b254851Vendor (CNA)
Linux Linux516001d53e6b2ea95a251ee2ef54a1a689a3fd58Vendor (CNA)
Linux Linux608b7751926ec08fae6a1ac4e7308195da68c362Vendor (CNA)
Linux Linux74375caa20fe5165807b4334c783d1790b01f02aVendor (CNA)
Linux Linuxa69baeac38677270656e85753d93856a076dee57Vendor (CNA)
azl3 kernel 6.6.157.1-1 on Azure Linux 3.06.6.158.1-1 · Release NotesMicrosoft (MSRC)
debian:linux6.1.190-1 · Debian:12Package registry (OSV)
debian:linux6.12.111-1 · Debian:13Package registry (OSV)
debian:linux-6.126.12.111-1~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.

—

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. Fix✗ → ✓

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References

Show all references (7 more)

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

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