VulnerabilityPublished 23 Oct 2026

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

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in d8a24b9e1774a93943caf68d48c5e17be432220b : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:18 UTC

Severity

High

Rated High by Threat Radar's AI analysis · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in d8a24b9e1774a93943caf68d48c5e17be432220b, 31c7b15b3716e8d0dad58d2c3cdf321dfd06f4be, 28bc1ef699610ee09ce3d46a00552f5a0a0144bd +3

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

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=5.9.13 <5.10	Fixed in d8a24b9e1774a93943caf68d48c5e17be432220b 31c7b15b3716e8d0dad58d2c3cdf321dfd06f4be 28bc1ef699610ee09ce3d46a00552f5a0a0144bd 5.10 3efe0e0944157fdd2072b4dc7eb0491a317ed272 00fbf71e74115f7628fc0880b855434b1e70c40c
LinuxLinux	Affected =5.10	Fixed in–

AI-suggested

A fix for this vulnerability is available in Linux kernel version 5.10 and later. Systems running affected versions (>=5.9.13 <5.10 and =5.10) should be upgraded to a fixed kernel release. No additional mitigation steps are indicated beyond applying the official patch.

Description

A vulnerability in the Linux kernel's packet_rcv_spkt() function could cause a kernel panic when processing packets on devices without a visible link layer header, such as CAN interfaces. This occurs because the function attempts to restore the link layer header without verifying its presence, leading to an invalid memory operation and system crash. The issue affects Linux kernel versions 5.9.13 through 5.10. The flaw has been fixed in Linux kernel version 5.10 and later.

Impact

A kernel panic can be triggered on affected Linux systems when a packet socket receives data on a device without a visible link layer header, such as a CAN interface. This results in a denial of service due to a fatal exception in interrupt context. The vulnerability is exploitable by creating a SOCK_PACKET socket bound to such an interface and sending a crafted frame, causing the system to crash.

Summary

The Linux kernel's packet_rcv_spkt() function restores the link layer header using skb_push() based on the difference between skb->data and skb_mac_header(skb). However, this subtraction is only valid if the device has a link layer header. Unlike related functions packet_rcv() and tpacket_rcv(), packet_rcv_spkt() lacks a guard check (dev_has_header()), which can lead to skb->mac_header retaining an invalid sentinel value (0xFFFF) on devices without a visible link layer header, such as CAN devices. This causes skb_push() to receive a large negative length, triggering skb_under_panic() and resulting in a kernel panic from softirq context. The vulnerability is reachable because packet_create() allows SOCK_PACKET sockets on CAN interfaces without additional length or capability checks. The missing skb_reset_*_header() calls in init_can_skb() are a related regression but are being fixed separately. The patch guards the skb_push() call in packet_rcv_spkt() similarly to other receive paths, preventing the panic. The fix is included in Linux kernel 5.10 and later.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:58 UTC

Technical details

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