CVE-2026-74325: wifi: mt76: use kfree_rcu for offchannel link in mt76_put_vif_phy_link
In the Linux kernel, the following vulnerability has been resolved:
wifi: mt76: use kfreercu for offchannel link in mt76putvifphylink
mt76putvifphylink() frees the offchannel mlink with plain kfree() after rcuassignpointer(NULL). However, rcuassignpointer only prevents future RCU readers from obtaining the pointer -- it does not wait for existing readers that already hold it via rcudereference.
The TX datapath (e.g. mt7996macwritetxwi) dereferences mlink->wcid and mlink->idx under rcureadlock. If a TX softirq obtained the pointer via rcudereference just before the NULL assignment, it will dereference freed memory after the kfree.
struct mt76viflink already contains an rcuhead field that is unused at this free site -- a developer oversight, since the adjacent kfreercumightsleep call for rxsc in the same function shows the pattern was understood.
Replace kfree(mlink) with kfreercu(mlink, rcuhead).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In mt76_put_vif_phy_link(), replace kfree(mlink) with kfree_rcu(mlink, rcu_head) when freeing the offchannel mlink after rcu_assign_pointer(NULL), so existing RCU readers cannot dereference freed memory.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74325?
CVE-2026-74325 has a risk score of 55.
How do I fix CVE-2026-74325?
To fix CVE-2026-74325, update your Linux kernel to the latest patched version that resolves this vulnerability.
What does CVE-2026-74325 affect?
CVE-2026-74325 affects the Linux kernel, specifically the mt76 driver related to Wi-Fi functionality.
What is the nature of the vulnerability in CVE-2026-74325?
CVE-2026-74325 involves improper memory management due to using kfree instead of kfree_rcu in handling offchannel links.
When was CVE-2026-74325 published?
CVE-2026-74325 was published on August 15, 2026.