VulnerabilityPublished 26 Oct 2026Updated 27 Oct 2026

CVE-2026-99033: Linux kernel · net/packet: guard the ll header push in packet_rcv_spkt()

Affects Linux kernelSource GCVE Database

Authoritative record:CVE-2026-99033· High

Not known to be exploited.

Data as of 28 Oct 2026, 01:45 UTC

Severity

High

Rated by Threat Radar · CVSS not yet scored by NVD

Exploitation evidence

Disclosed: evidence found.
CVE published 23 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.10linux`pkg:deb/ubuntu/linux?arch=source&distro=stonking`Other threats	Affected 7.0.0-14.14 – 7.3.0-9.9 6 affected builds	Fixed in–
Ubuntu 26.10linux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=stonking`Other threats	Affected 7.0.0-1004.4 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=stonking`Other threats	Affected 7.0.0-1004.4 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=stonking`Other threats	Affected =7.0.0-1004.4 =7.3.0-1002.3 =7.3.0-1003.4	Fixed in–
Ubuntu 26.10linux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=stonking`Other threats	Affected 7.0.0-1003.3 – 7.3.0-1003.3 5 affected builds	Fixed in–
Ubuntu 26.10linux-oracle`pkg:deb/ubuntu/linux-oracle?arch=source&distro=stonking`Other threats	Affected 7.0.0-1003.3 – 7.3.0-1003.3 5 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A patch has been applied to guard the skb_push() call in packet_rcv_spkt() with a check for the presence of a link layer header, preventing the kernel panic. Users should update to a kernel version that includes this fix. The affected versions listed should be upgraded or patched accordingly. No additional mitigation is required beyond applying the official fix.

Description

CVE-2026-99033 is a vulnerability in the Linux kernel's net/packet subsystem where the function packet_rcv_spkt() improperly handles the link layer header push operation. This can cause a kernel panic when processing CAN (Controller Area Network) packets on certain socket types due to an uninitialized mac_header pointer. The issue arises because packet_rcv_spkt() does not guard the skb_push() operation with a check for the presence of a link layer header, unlike similar functions. This flaw can lead to a fatal kernel panic from softirq context, causing a system crash.

Impact

This vulnerability causes a kernel panic leading to a denial of service on affected Linux systems when processing CAN packets via SOCK_PACKET sockets. The panic occurs in softirq context, resulting in a full system crash that cannot be recovered without reboot. There is no indication of privilege escalation or code execution, but the denial of service impact is significant for systems relying on CAN interfaces and packet sockets.

Summary

The vulnerability in the Linux kernel's net/packet subsystem involves the packet_rcv_spkt() function restoring the link layer header without verifying if the device has a valid link layer header. Specifically, skb_push() is called with a length derived from skb->data - skb_mac_header(skb), which is invalid if skb_mac_header() returns the sentinel 0xFFFF value. This occurs on CAN devices where the mac_header is not reset properly, leading to a large negative length passed to skb_push(), triggering skb_under_panic() and causing a kernel BUG and panic. The socket type SOCK_PACKET allows access to CAN interfaces without additional checks, making the panic reachable. The issue was fixed by adding a guard similar to other receive paths to prevent the invalid skb_push() call. The problem was confirmed on kernel versions tested with CONFIG_CAN_SLCAN enabled, and the patch prevents the kernel panic.

GCVE source: db.gcve.eu
OSV ID: UBUNTU-CVE-2026-99033
Osv Schema Version: 1.7.0
Ecosystems: Ubuntu:16.04:LTS, Ubuntu:18.04:LTS, Ubuntu:20.04:LTS, Ubuntu:Pro:20.04:LTS, Ubuntu:22.04:LTS, Ubuntu:Nvidia-BlueField:22.04:LTS, Ubuntu:Pro:Realtime:22.04:LTS, Ubuntu:Pro:FIPS-preview:22.04:LTS, Ubuntu:Pro:FIPS-updates:22.04:LTS, Ubuntu:24.04:LTS, Ubuntu:Nvidia-BlueField:24.04:LTS, Ubuntu:Pro:Realtime:24.04:LTS, Ubuntu:Pro:FIPS-updates:24.04:LTS, Ubuntu:26.10, Ubuntu:26.04:LTS

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 28 Oct 2026, 01:45 UTC

Technical details

References

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