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Linux KernelOperating system · Linux

CVE-2026-23270

HIGH · 7.8 CVSS v3.1 Published 2026-03-18
Fix available
A fix is available. Upgrade to 5.15.203 / 6.1.167 or later.
See remediation →
80/100
Remediation priority · High
Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
In the Linux kernel, the following vulnerability has been resolved: net/sched: Only allow act_ct to bind to clsact/ingress qdiscs and shared blocks As Paolo said earlier [1]: "Since the blamed commit below, classify can return TC_ACT_CONSUMED while the current skb being held by the defragmentation engine. As reported by GangMin Kim, if such packet is that may cause a UaF when the defrag engine later on tries to tuch again such packet." act_ct was never meant to be used in the egress path, however some users are attaching it to egress today [2]. Attempting to reach a middle ground, we noticed that, while most qdiscs are not handling TC_ACT_CONSUMED, clsact/ingress qdiscs are. With that in mind, we address the issue by only allowing act_ct to bind to clsact/ingress qdiscs and shared blocks. That way it's still possible to attach act_ct to egress (albeit only with clsact). [1] https://lore.kernel.org/netdev/674b8cbfc385c6f37fb29a1de08d8fe5c2b0fbee.1771321118.git.pabeni@redhat.com/ [2] https://lore.kernel.org/netdev/[email protected]/

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis
How this class of weakness works · CWE-416

Memory is used after it has been freed, so its contents — now potentially attacker-controlled — drive the program's behaviour. With careful heap grooming this becomes code execution. The fix requires disciplined ownership of memory and often a targeted rework of the object lifecycle.

General guidance for the use after free class — the official description and references above are authoritative for this specific CVE. Want a bespoke review and a reviewed fix? Ask our team →

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Linux KernelOperating system
Affected:>= 5.15.148, < 5.15.203>= 6.1.75, < 6.1.167>= 6.6.14, < 6.6.130>= 6.7.2, < 6.8>= 6.8, < 6.12.77>= 6.13, < 6.18.18>= 6.19, < 6.19.8= 7.0

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 5.15.203 / 6.1.167 / 6.6.130 or later
Fixed in 5.15.2036.1.1676.6.130
Vendor patch git.kernel.org →
Recommended fix High confidence

Kernel 5.15.203+ (5.15.x), 6.1.167+ (6.1.x), 6.6.130+ (6.6.x), or 6.8+ (6.7.x/6.8.x)

  1. Identify the currently running kernel version using 'uname -r'
  2. Determine which major kernel series you are running (5.15.x, 6.1.x, 6.6.x, or 6.7.x)
  3. For 5.15.x: Upgrade to kernel version 5.15.203 or later using your distribution's package manager
  4. For 6.1.x: Upgrade to kernel version 6.1.167 or later using your distribution's package manager
  5. For 6.6.x: Upgrade to kernel version 6.6.130 or later using your distribution's package manager
  6. For 6.7.x: Upgrade to kernel version 6.8 or later using your distribution's package manager
  7. Reboot the system to load the new kernel
  8. Verify the fix is applied by checking the kernel version with 'uname -r' and confirming it meets the minimum fixed version for your series
Caveat Upgrading kernel may require rebooting and could introduce changes in driver/module compatibility; ensure critical modules are available in the new kernel

Generated from the published advisory — verify against the referenced sources before acting.

We can perform the upgrade in your staging environment and verify nothing breaks — typical engagement from $3,200. Get the upgrade done

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-23270 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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