Copyright © 2012 Red Hat, Inc. All rights reserved. Moderate 2026-10-18T15:46:38 kernel: kernel: mac80211: Denial of Service via use-after-free in channel context replacement 4.7 CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H CWE-416

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: keep paired old chanctx alive An in-place replacement keeps reciprocal replace_ctx pointers between the old WILL_BE_REPLACED chanctx and the new REPLACES_OTHER chanctx. However, the early free paths only consider assigned and reserved link users when deciding whether to free the old chanctx. That lets the old chanctx be freed too early while the replacement partner still points back to it, either when the last assigned link is released or when that link successfully reassigns to another existing context. Later unreserve and switch-finalization paths can then follow a stale replace_ctx pointer. Keep a paired old chanctx alive until the replacement pair has been torn down. Apply the same check to both __ieee80211_link_release_channel() and ieee80211_link_use_reserved_reassign(). If the replacement is later abandoned, ieee80211_link_unreserve_chanctx() already tears down the pairing before freeing the old chanctx once no users remain.

A flaw was found in the Linux kernel's mac80211 wireless subsystem. A local user could exploit this flaw to cause a Denial of Service (DoS) or system instability. During in-place channel context replacement, an old channel context can be freed prematurely while still referenced by its replacement context. Subsequent link operations access the stale pointer, triggering a use-after-free condition that leads to a kernel crash.

A lifetime management flaw in mac80211 can free an old WILL_BE_REPLACED channel context while its REPLACES_OTHER partner still retains a reciprocal replace_ctx pointer. A later unreserve or switch finalization path can follow this stale pointer and cause a use after free, with a possible repeated free of the old channel context depending on the later cleanup path. Impact is at least a local denial of service through kernel memory corruption and a kernel crash. In the worst still defensible case the stale kernel object may permit confidentiality and integrity impact or local privilege escalation, although a controllable write primitive is not proven by the supplied code. For the CVSS the PR:L reflects a local user or service with delegated wireless configuration capability rather than an unauthenticated remote attacker. AC:H reflects the required multi-vif in-place replacement and teardown sequence. The issue is not directly network reachable based on the supplied paths, and wireless traffic alone is not sufficient evidence of remote triggering. Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Red Hat Enterprise Linux 10 Fix deferred kernel https://www.cve.org/CVERecord?id=CVE-2026-98708 https://nvd.nist.gov/vuln/detail/CVE-2026-98708 https://git.kernel.org/stable/c/1c82d0c5d509179ba2a4edfa096f516aebf960b0 https://git.kernel.org/stable/c/21a688cbeae0e682f03e91f1e7a7eedd60d9d4f2 https://git.kernel.org/stable/c/3412e9a800786d1dec4a58367db1cba275e7ef11 https://git.kernel.org/stable/c/afd1cdd16a25c7185b812a612ab7d5f2cbd1e086 https://kernelcve.org/list/?q=CVE-2026-98708