UDP traffic disruption via post-segmentation conntrack check
Published May 27, 2026 · Updated May 27, 2026
Denial of service in the Linux Kernel nfnetlink_queue path allows remote attackers to drop queued UDP traffic via GSO packets. The shared-unconfirmed conntrack check runs after skb_gso_segment(), whose clones raise the reference count and cause nf_ct_drop_unconfirmed() to discard every segment. The condition requires an nfqueue application without F_GSO, a GSO UDP packet, and an unconfirmed conntrack entry; affected traffic is dropped rather than queued.
Summary
What happened
Denial of service in the Linux Kernel nfnetlink_queue path allows remote attackers to drop queued UDP traffic via GSO packets. The shared-unconfirmed conntrack check runs after skb_gso_segment(), whose clones raise the reference count and cause nf_ct_drop_unconfirmed() to discard every segment. The condition requires an nfqueue application without F_GSO, a GSO UDP packet, and an unconfirmed conntrack entry; affected traffic is dropped rather than queued.
The record
- CVE
- CVE-2026-45859
- Published
- May 27, 2026
- Updated
- May 27, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux Kernel
- Classifications
- T1498
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- May 27, 2026CVE publishedPublication date reported by the CVE source.
- May 27, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=025b3326c5c409b372d0103ad30f174e55adbd1b
- Affected versionversion=5.15.166 <5.16
- Affected versionversion=6.10.7 <6.11
- Affected versionversion=6.11
- Affected versionversion=6.1.107 <6.2
- Affected versionversion=6.6.48 <6.7
- Affected versionversion=6c4a0ba674f410ab99a30a16f32dac0ebfed5cd3
- Affected versionversion=6dcc8ba8a6074bb79040f502dc66ad23a58a1c86
- Affected versionversion=74e6eb7fd27ef1ccc68041dbc66e6d80d2e4a1a0
- Affected versionversion=7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb <207b3ebacb6113acaaec0d171d5307032c690004
- Affected versionversion=7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb <23901aa6b8a2f294c4b774436b4691f3ff863a8f
- Affected versionversion=7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb <79b713ef4261a8ead96af4703f89d0b5f25532e2
- Affected versionversion=7d8dc1c7be8d3509e8f5164dd5df64c8e34d7eeb <b740e7ddd7ca0dbfeafca3f5e52717206cf28524
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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