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Linux KernelOperating system · Linux

CVE-2026-45859

HIGH · 7.5 CVSS v3.1 Published 2026-05-27
Fix available
A fix is available. Upgrade to 5.16 / 6.2 or later.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges 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: netfilter: nfnetlink_queue: do shared-unconfirmed check before segmentation Ulrich reports a regression with nfqueue: If an application did not set the 'F_GSO' capability flag and a gso packet with an unconfirmed nf_conn entry is received all packets are now dropped instead of queued, because the check happens after skb_gso_segment(). In that case, we did have exclusive ownership of the skb and its associated conntrack entry. The elevated use count is due to skb_clone happening via skb_gso_segment(). Move the check so that its peformed vs. the aggregated packet. Then, annotate the individual segments except the first one so we can do a 2nd check at reinject time. For the normal case, where userspace does in-order reinjects, this avoids packet drops: first reinjected segment continues traversal and confirms entry, remaining segments observe the confirmed entry. While at it, simplify nf_ct_drop_unconfirmed(): We only care about unconfirmed entries with a refcnt > 1, there is no need to special-case dying entries. This only happens with UDP. With TCP, the only unconfirmed packet will be the TCP SYN, those aren't aggregated by GRO. Next patch adds a udpgro test case to cover this scenario.

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

A detailed technical summary for this CVE is being prepared.

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:>= 5.15.166, < 5.16>= 6.1.107, < 6.2>= 6.6.48, < 6.7>= 6.10.7, < 6.11>= 6.11.1, < 6.12.75>= 6.13, < 6.18.14>= 6.19, < 6.19.4= 6.11

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
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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 5.16 / 6.2 / 6.7 or later
Fixed in 5.166.26.7
Vendor patch git.kernel.org →
Recommended fix High confidence

Linux kernel 5.16, 6.2, 6.7, or 6.11 (whichever is compatible with your distribution)

  1. Identify the current running kernel version using 'uname -r'
  2. Check if the current version is affected: >= 5.15.166 and < 5.16, OR >= 6.1.107 and < 6.2, OR >= 6.6.48 and < 6.7, OR >= 6.10.7 and < 6.11
  3. If affected, upgrade the kernel to a fixed release: 5.16 or later, 6.2 or later, 6.7 or later, or 6.11 or later
  4. For enterprise distributions, apply the vendor-specific kernel update patch or upgrade the kernel package
  5. Reboot the system to load the fixed kernel
  6. Verify the fix by checking the kernel version and confirming the commit 207b3ebacb6113acaaec0d171d5307032c690004 is included
Caveat Kernel upgrades may require system reboot and could introduce compatibility issues with out-of-tree kernel modules or proprietary drivers; test in non-production environment first

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 $1,950. 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-2026-45859 in production — separate from our analysis above.

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What this is

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