Medium [CVE-2026-74366] fix NULL deref in change_sta_links for unready link
This medium-severity Red Hat Linux advisory covers CVE-2026-74366 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat package: kernel-rt.
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Summary
In the Linux kernel, the following vulnerability has been resolved: wifi: ath12k: fix NULL deref in change_sta_links for unready link _ieee80211_set_active_links() calls _ieee80211_link_use_channel() for each newly-added link and WARN_ON_ONCE()s if it fails.
The call uses assign_on_failure=true, which allows mac80211 to continue despite driver failures, but when a mac80211-level channel validation fails (e.g., combinations check, DFS, or no available radio), drv_assign_vif_chanctx() is never reached.
Since ath12k_mac_vdev_create() is only called from that path, arvif->is_created remains false and arvif->ar remains NULL for the failed link. The subsequent drv_change_sta_links() call reaches ath12k_mac_op_change_sta_links(), which allocates an arsta and sets ahsta->links_map |= BIT(link_id) for the broken link before checking whether the link is ready.
When the vdev was never created, only station_add() is skipped, but the link remains in links_map. Any subsequent operation iterating links_map and dereferencing arvif->ar without a NULL check will crash.
Two observed examples are NULL deref in ath12k_mac_ml_station_remove() on disconnect and in ath12k_mac_op_set_key() when wpa_supplicant installs PTK keys.
Affected products named by the advisory: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat package: kernel-rt.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 1 hour ago·verify at source
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