VulnerabilityPublished 18 Oct 2026

CVE-2026-98797: Linux kernel · net: cap skb->queue_mapping when the tx queue is picked

Affects Linux kernelSource CVE Database V5

Not known to be exploited · fixed in f99de42f5c6f8d088063817dad82c3334e87c570 : patch Linux kernel soon.

Data as of 26 Oct 2026, 12:55 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 5% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in f99de42f5c6f8d088063817dad82c3334e87c570, ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d, c6ec35c8267c84c2094cb485db20c06384fc2bcc +1

Exploitation evidence

Disclosed: evidence found.
CVE published 18 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 Linux kernel to f99de42f5c6f8d088063817dad82c3334e87c570, ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d, c6ec35c8267c84c2094cb485db20c06384fc2bcc or 2f581814e4e3ea6a5e98f49813dc4c68444a0c4a.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 2f1e85b1aee459b7d0fd981839042c6a38ffaf0c, < f99de42f5c6f8d088063817dad82c3334e87c570	Fixed in f99de42f5c6f8d088063817dad82c3334e87c570
LinuxLinux	Affected ≥ 2f1e85b1aee459b7d0fd981839042c6a38ffaf0c, < ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d	Fixed in ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d
LinuxLinux	Affected ≥ 2f1e85b1aee459b7d0fd981839042c6a38ffaf0c, < c6ec35c8267c84c2094cb485db20c06384fc2bcc	Fixed in c6ec35c8267c84c2094cb485db20c06384fc2bcc
LinuxLinux	Affected ≥ 2f1e85b1aee459b7d0fd981839042c6a38ffaf0c, < 2f581814e4e3ea6a5e98f49813dc4c68444a0c4a	Fixed in 2f581814e4e3ea6a5e98f49813dc4c68444a0c4a
LinuxLinux	Affected =5.19	Fixed in–

AI-suggested

The vulnerability has been fixed in the Linux kernel by commits f99de42f5c6f8d088063817dad82c3334e87c570, ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d, c6ec35c8267c84c2094cb485db20c06384fc2bcc, and 2f581814e4e3ea6a5e98f49813dc4c68444a0c4a. Users and administrators should apply these kernel updates to remediate the issue. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-98797 is a vulnerability in the Linux kernel's network stack involving improper handling of skb->queue_mapping during packet transmission. The flaw allows a local user with CAP_NET_ADMIN in a network namespace to redirect packets from a device with more TX queues to one with fewer, causing out-of-bounds access in the taprio_enqueue function. This occurs because stale queue_mapping values from the ingress device are used by the egress device, leading to potential memory corruption. The issue is fixed by properly capping skb->queue_mapping and managing related flags during packet transmission.

Impact

A local user with CAP_NET_ADMIN privileges in a network namespace can cause the kernel to perform out-of-bounds memory accesses during packet transmission by redirecting packets from devices with more TX queues to devices with fewer TX queues using crafted skb->queue_mapping values. This can lead to memory corruption, kernel faults under KASAN, and potential system instability or denial of service. No public exploits or in-the-wild exploitation are known.

Summary

The vulnerability arises from skbedit setting skb->queue_mapping and raising a per-CPU skip_txqueue flag that __dev_queue_xmit() honors. However, __dev_queue_xmit() clears this flag before sch_handle_egress() and only reads it afterward, allowing nested transmissions to improperly consume the flag for packets that never went through skbedit. Forwarded packets retain the ingress NIC's rx_queue + 1 in skb->queue_mapping, causing the outer device to index its tx queue state with a stale value. In devices using taprio qdiscs, this leads to out-of-bounds array access and dereferencing invalid pointers. The fix involves restricting the skip_txqueue flag to only be raised during egress classification inside sch_handle_egress(), saving and restoring the flag around the egress hook, and capping skb->queue_mapping to valid device queue counts. The vulnerability can be triggered by a local user with CAP_NET_ADMIN in a network namespace without requiring eBPF programs, under specific kernel configurations involving taprio, skbedit, mirred, and clsact qdiscs. The issue is addressed in several Linux kernel commits identified by hashes f99de42f5c6f8d088063817dad82c3334e87c570, ea4d4b5dddb5121e64f56fd8e0720bd8b447b63d, c6ec35c8267c84c2094cb485db20c06384fc2bcc, and 2f581814e4e3ea6a5e98f49813dc4c68444a0c4a.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Oct 2026, 09:57 UTC

Technical details

References

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