UBUNTU-CVE-2026-43238: Medium severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: net/sched: actskbedit: fix divide-by-zero in tcfskbedithash() Commit 38a6f0865796 ("net: sched: support hash selecting tx queue") added SKBEDITFTXQSKBHASH support. The inclusive range size is computed as: mappingmod = queuemappingmax - queuemapping + 1; The range size can be 65536 when the requested range covers all possible u16 queue IDs (e.g. queuemapping=0 and queuemappingmax=U16MAX). That value cannot be represented in a u16 and previously wrapped to 0, so tcfskbedithash() could trigger a divide-by-zero: queuemapping += skbgethash(skb) % params->mappingmod; Compute mappingmod in a wider type and reject ranges larger than U16MAX to prevent params->mappingmod from becoming 0 and avoid the crash.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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ubuntu/linux-aws-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1060.63~22.04.1 - Upgrade
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ubuntu/linux-azure-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1063.71~22.04.1 - Upgrade
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ubuntu/linux-azure-fde-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1062.69~22.04.1 - Upgrade
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1063.69~22.04.1 - Upgrade
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ubuntu/linux-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-136.136~22.04.1 - Upgrade
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ubuntu/linux-ibm-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1060.61~22.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-134.134.1~22.04.1 - Upgrade
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ubuntu/linux-nvidia-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1058.61~22.04.1 - Upgrade
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ubuntu/linux-oracle-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1057.58~22.04.1 - Upgrade
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ubuntu/linux-riscv-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-134.134~22.04.1 - Upgrade
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ubuntu/linux-realtime-6.8to a version that resolves this vulnerability.Fixed in 6.8.1-1055.56~22.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-134.134 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1060.63 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1063.71 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 6.8.0-1062.69 - Upgrade
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ubuntu/linux-azure-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1039.42 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1063.69 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1058.64 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1045.48 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1060.61 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-134.134.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1058.61 - Upgrade
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ubuntu/linux-nvidia-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-1058.61.1 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 6.8.0-1029.30 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1057.58 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.8.0-1060.64 - Upgrade
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ubuntu/linux-xilinxto a version that resolves this vulnerability.Fixed in 6.8.0-1032.33 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 6.8.0-1026.30 - Upgrade
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ubuntu/linux-raspi-realtimeto a version that resolves this vulnerability.Fixed in 6.8.0-2049.50 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1055.56 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1060.63+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1062.69+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-134.134+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-1063.69+fips1
Event History
Frequently Asked Questions
Who is exposed to this issue?
Systems using the listed Ubuntu Linux kernel packages are exposed if they can apply an skbedit traffic-control action with SKBEDIT_F_TXQ_SKBHASH and a queue-ID range covering all possible u16 queue IDs.
What does an attacker need to trigger the crash?
The attack vector is local and requires low privileges. Exploitation requires configuring the skbedit hash-based transmit-queue selection range so that queue_mapping is 0 and queue_mapping_max is U16_MAX, or another range whose inclusive size is 65536.
What is the impact of a successful trigger?
The range-size calculation can wrap to zero, causing a divide-by-zero in tcf_skbedit_hash() when calculating the queue mapping. The stated impact is availability loss.
How can I determine whether a system has a risky configuration?
Inspect skbedit traffic-control actions using hash-based transmit-queue selection and check whether their configured inclusive queue-mapping range contains 65,536 IDs. A range from 0 through U16_MAX is specifically identified as triggering the condition.
What mitigation is available before applying the fix?
Avoid configuring SKBEDIT_F_TXQ_SKBHASH with a queue-mapping range whose inclusive size is 65,536. In particular, do not use queue_mapping=0 together with queue_mapping_max=U16_MAX.