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NVD / CVE Program· CNA Linux

CVE-2026-97959: net/sched: cls_route: free emptied bucket on filter move

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 1853f30cf5c84971f99788a76207c6f745380896, 2e2f130951d34871b0643bf700164d97cff4b427, 41e94079200aaf0cdbe4594b0af75710b33da124; 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 1853f30cf5c84971f99788a76207c6f745380896, 2e2f130951d34871b0643bf700164d97cff4b427, 41e94079200aaf0cdbe4594b0af75710b33da124; 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: net/sched: cls_route: free emptied bucket on filter move route4_change can move an existing filter to a different top-level bucket: route4_set_parms recomputes the handle from TCA_ROUTE4_TO/ FROM/IIF, and the handle-mismatch check is gated on the 'new' flag, so for an existing filter the new handle may differ from the old one and land in a different bucket. When this happens, the filter is unlinked from the old bucket, but the bucket itself is never freed once it goes empty. The stale empty bucket remains in head->table[], causing route4_delete to report *last=false even after the last live filter is gone. That pins the empty tcf_proto and causes a leak. Fix this by refcounting the filters linked to a bucket and freeing the bucket when the count drops to zero. The existing scan in route4_delete goes away with it. The count is updated at all sites that link or unlink a filter during add, change and delete, and the bucket is dropped from head->table[] as soon as it reaches zero. Conditions to recreate the bug: CONFIG_NET_CLS_ROUTE4=y, CONFIG_NET_SCH_INGRESS=y, CONFIG_NET_CLS_ACT=y. tc qdisc replace dev lo clsact tc filter add dev lo ingress protocol ip pref 100 route from 1 to 1 tc filter change dev lo ingress protocol ip pref 100 handle 0x10001 \ route from 1 to 2 tc filter del dev lo ingress protocol ip pref 100 handle 0x10002 \ route from 1 to 2 tc filter show dev lo ingress | grep -c 'pref 100 route chain 0 '

—No exploit Fix available
Published
Sep 25, 2026
Updated
Oct 19, 2026
EPSS
0.1% · 7th 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%

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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

    • 4.1affected
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 9e7741b41a25b9d49df4d262fa314342e6f95c50affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 48d38bf8c22a05fde07ba1f885cde27b851649a2affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before cc99d26b12431e4e4d0e346ec32764eb42c0aed9affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 41e94079200aaf0cdbe4594b0af75710b33da124affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 2e2f130951d34871b0643bf700164d97cff4b427affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before f8495d67434e1cb7e511297687ca55fdb28e4c20affected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 81dd117c04422c6d0c7974aba9fa6a0ba370959baffected · git
    • 1e052be69d045c8d0f82ff1116fd3e5a79661745 and later · before 1853f30cf5c84971f99788a76207c6f745380896affected · git
    • before 4.1not affected · 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-2026-97957Sep 25, 2026 · net: hinic: fix mailbox segment buffer overflow
    35Monitor
  • ← EarlierCVE-2026-97958Sep 25, 2026 · net/sched: cls_api: Don't replay RTM_GETCHAIN in tc_ctl_chain().
    0Monitor
  • Later →CVE-2026-97960Sep 25, 2026 · perf/x86/intel: Prevent drain_pebs() reentry
    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 Linux1853f30cf5c84971f99788a76207c6f745380896Vendor (CNA)
Linux Linux2e2f130951d34871b0643bf700164d97cff4b427Vendor (CNA)
Linux Linux41e94079200aaf0cdbe4594b0af75710b33da124Vendor (CNA)
Linux Linux48d38bf8c22a05fde07ba1f885cde27b851649a2Vendor (CNA)
Linux Linux81dd117c04422c6d0c7974aba9fa6a0ba370959bVendor (CNA)
Linux Linux9e7741b41a25b9d49df4d262fa314342e6f95c50Vendor (CNA)
Linux Linuxcc99d26b12431e4e4d0e346ec32764eb42c0aed9Vendor (CNA)
Linux Linuxf8495d67434e1cb7e511297687ca55fdb28e4c20Vendor (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.

All records