VulnerabilityPublished 26 Aug 2026Updated 30 Sep 2026

CVE-2026-74742: Linux kernel · veth: fix queue index used to wake the peer txq in veth_poll

Affects Linux kernelSource GCVE Database

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 14:05 UTC

CVSS 3.1 base score

7.5High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 26 Aug 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-pp8f-5mj5-qp78

What to do

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-34.34 22 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1013.13 14 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1014.14 14 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1013.13 8 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1013.13 12 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1007.8 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 fix has been implemented in the Linux kernel to correctly derive the peer TX queue index regardless of XDP program attachment. Users should apply the official kernel updates that include this fix. Since this is a kernel-level issue, upgrading to a patched kernel version is the recommended remediation. No additional mitigations are indicated.

Description

In the Linux kernel, the following vulnerability has been resolved: veth: fix queue index used to wake the peer txq in veth_poll veth_poll() derives the index of the peer TX queue to wake from rq->xdp_rxq.queue_index. That field is only initialized by xdp_rxq_info_reg() in veth_enable_xdp_range(), which runs only when an XDP program is attached. On the plain GRO/NAPI path (veth_napi_enable_range()) xdp_rxq_info_reg() is never called, so queue_index stays 0 for every queue, as priv->rq is zero-allocated. So in a multi-queue setup with GRO enabled and no XDP program attached, every NAPI instance looks at the peer's TX queue 0. If veth_xmit() stops peer TX queue 1 because the ptr_ring is full (NETDEV_TX_BUSY), nothing ever wakes it again: the poller draining queue 1 wakes queue 0 instead. veth implements no ndo_tx_timeout, so the netdev watchdog does not kick in either, and the queue stays stopped indefinitely. Derive the index from the position of the rq within priv->rq instead, which is correct regardless of whether XDP was ever enabled. Scripts to reproduce the stall are available at https://github.com/netoptimizer/veth-backpressure-performance-testing

Impact

This vulnerability results in a denial of service condition on the affected veth network interface by causing one or more transmit queues to stall indefinitely. This impacts availability but does not affect confidentiality or integrity. There is no indication of active exploitation in the wild.

Summary

The Linux kernel's veth_poll() function incorrectly derives the index of the peer TX queue to wake from rq->xdp_rxq.queue_index, which is only initialized when an XDP program is attached. Without XDP, this field remains zero, causing all NAPI instances to wake peer TX queue 0 regardless of the actual queue that is stalled. If a peer TX queue (e.g., queue 1) is stopped due to a full ptr_ring (NETDEV_TX_BUSY), it is never woken again because the poller wakes queue 0 instead. Since veth does not implement ndo_tx_timeout, the queue remains stalled indefinitely. The fix derives the index from the position of rq within priv->rq, which is correct regardless of XDP usage. This vulnerability can cause a denial of service by stalling network traffic on affected queues.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 10 Sep 2026, 06:54 UTC

Technical details

References

Community reviews

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