CVE-2026-98887: wifi: mac80211_hwsim: reject undersized HWSIM_ATTR_TX_INFO
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211hwsim: reject undersized HWSIMATTRTXINFO
hwsimtxinfoframereceivednl() casts the HWSIMATTRTXINFO payload to a struct hwsimtxrate and unconditionally reads IEEE80211TXMAXRATES entries (8 bytes) from it. The policy only bounds the attribute from above (NLABINARY .len is a maximum) and the op sets GENLDONTVALIDATESTRICT, so a short or zero-length attribute is accepted and the loop reads past the payload.
Require the exact length in the policy, so a malformed attribute is rejected before the handler runs.
Affected Software
Remediation
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Require the HWSIM_ATTR_TX_INFO attribute to have the exact length of IEEE80211_TX_MAX_RATES entries (8 bytes) so undersized or zero-length attributes are rejected before hwsim_tx_info_frame_received_nl() runs.
Linux kernel mac80211_hwsim HWSIM_ATTR_TX_INFO NLA_BINARY policy length = exact length: IEEE80211_TX_MAX_RATES entries (8 bytes)
Event History
Frequently Asked Questions
Who can trigger the out-of-bounds read?
An attacker able to send a crafted generic netlink message to the mac80211_hwsim interface can supply an undersized or zero-length HWSIM_ATTR_TX_INFO attribute. The provided data does not specify the privileges or access controls required to send such a message.
Are normal, correctly formed TX_INFO attributes affected?
The issue is triggered by malformed HWSIM_ATTR_TX_INFO payloads shorter than the handler expects. Correctly sized attributes are not described as causing the out-of-bounds read.
What changes in the fix?
The fix requires HWSIM_ATTR_TX_INFO to have the exact expected length in the netlink policy. Undersized attributes are then rejected before hwsim_tx_info_frame_received_nl() processes them.
How can I determine whether a system has the fix?
Check whether the kernel includes one of the referenced stable commits: 3a96bb65b4b820d8b41fa155781ec1c29e3479d4, 59e1f2a0242232b4a3af144ae317d3913fc09046, or 1ae85bb34fe3510659b86d6a5f8036dd498233f8.