VulnerabilityPublished 28 Oct 2026

CVE-2026-99192: Linux kernel · net: bcmgenet: unshare the skb before writing the control block

Source GCVE Database

Authoritative record:CVE-2026-99192

Not known to be exploited · fixed in 89771ce4f8f67dcffae561b2ccac95c0f6e3aa01 : update Linux kernel when convenient.

Data as of 28 Oct 2026, 13:43 UTC

Severity

Medium

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

Patch: Available – fixed in 89771ce4f8f67dcffae561b2ccac95c0f6e3aa01, 7939ad3b4db9eadf45a64f0524f38337a9494672, 40c04abcbc34e3afe338f41dae851ecbd72852ac +1

Exploitation evidence

Disclosed: evidence found.
CVE published 28 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.

ghsa-gcjx-rww2-6xmm

What to do

Upgrade Linux kernel to 89771ce4f8f67dcffae561b2ccac95c0f6e3aa01, 7939ad3b4db9eadf45a64f0524f38337a9494672, 40c04abcbc34e3afe338f41dae851ecbd72852ac or 3.17.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected >=3.16.50 <3.17	Fixed in 89771ce4f8f67dcffae561b2ccac95c0f6e3aa01 7939ad3b4db9eadf45a64f0524f38337a9494672 40c04abcbc34e3afe338f41dae851ecbd72852ac 3.17
LinuxLinux	Affected =4.13	Fixed in–

AI-suggested

A fix is available that unshares the skb before writing to the control block, preventing the overwrite issue. Users should apply the official kernel patch that addresses this vulnerability. Since no vendor advisory or patch links are provided, check the Linux kernel mailing lists or distribution security advisories for the official fix. Until patched, avoid using pktgen in clone_skb mode on affected kernel versions to prevent triggering the issue.

Description

A vulnerability in the Linux kernel's bcmgenet network driver involves improper handling of shared socket buffers (skb). The driver writes to the skb control block without unsharing it first, causing transmit queue stalls due to incorrect byte accounting in Byte Queue Limits (BQL). This issue was reproducible using pktgen in clone_skb mode, leading to a stalled transmit queue until a watchdog reset occurs.

Impact

The vulnerability causes the Byte Queue Limits (BQL) to stall the transmit queue because bytes are not properly credited when shared skbs are overwritten. This leads to network transmission stalls until the kernel watchdog resets the queue. There is no indication of remote code execution or privilege escalation, but network performance and reliability are affected.

Summary

The Linux kernel bcmgenet driver stores metadata in the skb control block and reads it back upon transmission completion to manage skb freeing and BQL crediting. However, the driver fails to unshare the skb before writing to the control block, allowing overwrites of control data when shared skbs are resubmitted. This results in incomplete byte crediting and stalls the transmit queue. The problem manifests when using pktgen with clone_skb mode, which reuses the same skb while earlier copies remain in the ring buffer. The fix involves unsharing the skb before modifying the control block to prevent data corruption and queue stalls.

References

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