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NVD / CVE Program· CNA Linux

CVE-2026-31422: net/sched: cls_flow: fix NULL pointer dereference on shared blocks

Noroxi assessment

Priority: Monitor (action score 22/100)

  • 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: 0.12% (FIRST EPSS).
  • Someone with local access to the system can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
  • Fixed version: Linux Linux 1a280dd4bd1d616a01d6ffe0de284c907b555504, 415ea0c973c754b9f375225807810eb9045f4293, 4a09f72007201c9f667dc47f64517ec23eea65e5; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2.

Low priority for now. Upgrade to Linux Linux 1a280dd4bd1d616a01d6ffe0de284c907b555504, 415ea0c973c754b9f375225807810eb9045f4293, 4a09f72007201c9f667dc47f64517ec23eea65e5; azl3 kernel 6.6.130.1-3 on Azure Linux 3.0 6.6.134.1-2 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_flow: fix NULL pointer dereference on shared blocks flow_change() calls tcf_block_q() and dereferences q->handle to derive a default baseclass. Shared blocks leave block->q NULL, causing a NULL deref when a flow filter without a fully qualified baseclass is created on a shared block. Check tcf_block_shared() before accessing block->q and return -EINVAL for shared blocks. This avoids the null-deref shown below: ======================================================================= KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:flow_change (net/sched/cls_flow.c:508) Call Trace: tc_new_tfilter (net/sched/cls_api.c:2432) rtnetlink_rcv_msg (net/core/rtnetlink.c:6980) [...] =======================================================================

MediumCVSS 5.5 · v3.1—No exploit Fix available
Published
Apr 13, 2026
Updated
Oct 15, 2026
EPSS
0.1% · 2th percentile

Report tools

JSON

Action score

22

Monitor

Low priority for now.

CVSS
22 / 40 · 5.5 / 10
CISA KEV
0 / 30 · Not listed
EPSS
0 / 30 · 0.1%

Get told when this record changes

  • Not in KEV: no record of exploitation in the wild
  • No public exploit code on record
  • A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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When you'll hear from us

  • when it enters CISA KEV
  • when exploit code appears or is weaponized
  • when the record is updated (including a fixed version)
  • when EPSS rises 20 points in a week

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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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.

VendorProduct
linuxlinux kernel

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

  • linux linux kernel4.15 and later · before 5.10.253
  • linux linux kernel5.11 and later · before 5.15.203
  • linux linux kernel5.16 and later · before 6.1.168
  • linux linux kernel6.2 and later · before 6.6.134
  • linux linux kernel6.7 and later · before 6.12.81
  • linux linux kernel6.13 and later · before 6.18.22
  • linux linux kernel6.19 and later · before 6.19.12
  • linux linux kernel7.0

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

    • 4.15affected
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 57f94ac7e953eece5ed4819605a18f3cdfc63dccaffected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 942813276edeb1741fa5b0a73471beb4e495fa08affected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before cc707a4fd4c3b6ab2722e06bc359aa010e13d408affected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 4a09f72007201c9f667dc47f64517ec23eea65e5affected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957eaffected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before a208c3e1232997e9317887294c20008dfcb75449affected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 415ea0c973c754b9f375225807810eb9045f4293affected · git
    • 1abf272022cf1d18469405f47b4ec49c6a3125db and later · before 1a280dd4bd1d616a01d6ffe0de284c907b555504affected · git
    • before 4.15not affected · semver

Package-level exposure

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

EcosystemPackageAffected rangeFix
Debian:12linuxbefore 6.1.170-16.1.170-1
Debian:13linuxbefore 6.12.85-16.12.85-1
Debian:14linuxbefore 6.19.12-16.19.12-1

Same product

linux: all records

Other highest-scoring records for the same primary product.

  • CVE-2026-31431crypto: algif_aead - Revert to operating out-of-placeKEV
    90Now
  • CVE-2022-0847A flaw was found in the way the "flags" member of the new pipe buffer structure was lacking proper initialization in copy_page_to_iter_pipe KEV
    89Now
  • CVE-2021-22555Heap Out-Of-Bounds Write in Netfilter IP6T_SO_SET_REPLACEKEV
    85Now

Published before and after this one in the same product

  • ← EarlierCVE-2026-31419Apr 13, 2026 · net: bonding: fix use-after-free in bond_xmit_broadcast()
    31Monitor
  • ← EarlierCVE-2026-31421Apr 13, 2026 · net/sched: cls_fw: fix NULL pointer dereference on shared blocks
    22Monitor
  • Later →CVE-2026-31423Apr 13, 2026 · net/sched: sch_hfsc: fix divide-by-zero in rtsc_min()
    22Monitor

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 Linux1a280dd4bd1d616a01d6ffe0de284c907b555504Vendor (CNA)
Linux Linux415ea0c973c754b9f375225807810eb9045f4293Vendor (CNA)
Linux Linux4a09f72007201c9f667dc47f64517ec23eea65e5Vendor (CNA)
Linux Linux57f94ac7e953eece5ed4819605a18f3cdfc63dccVendor (CNA)
Linux Linux942813276edeb1741fa5b0a73471beb4e495fa08Vendor (CNA)
Linux Linux9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957eVendor (CNA)
Linux Linuxa208c3e1232997e9317887294c20008dfcb75449Vendor (CNA)
Linux Linuxcc707a4fd4c3b6ab2722e06bc359aa010e13d408Vendor (CNA)
azl3 kernel 6.6.130.1-3 on Azure Linux 3.06.6.134.1-2 · CBL-Mariner ReleasesMicrosoft (MSRC)
debian:linux6.1.170-1 · 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.

No history yet (it accumulates with the daily EPSS job).

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).

Technical details

Attack conditions

  • Someone with local access to the system can trigger it.
  • A low-privileged account is enough.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
none
Integrity
none
Availability
high · the service can be disrupted
Attack vector
Local
Attack complexity
Low
Privileges required
Low
User interaction
None
Scope
Unchanged
Confidentiality impact
None
Integrity impact
None
Availability impact
High

Weakness class (CWE)

CWE-476 · NULL Pointer Dereference

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

nvd-primary

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✗ → ✓

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

References

Show all references (10 more)

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

All records