CVE-2026-74336 wifi: mac80211: bound S1G TIM PVB walk to the TIM element
An out-of-bounds read in the Linux kernel Wi-Fi driver allows attackers to read adjacent memory data via crafted S1G TIM elements.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-74336?
CVE-2026-74336 is a vulnerability in Linux, published on 15 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
In the Linux kernel, the following vulnerability has been resolved:
wifi: mac80211: bound S1G TIM PVB walk to the TIM element
ieee80211_s1g_check_tim() parses the S1G Partial Virtual Bitmap (PVB) of a received TIM element. The TIM is handed in as the element payload: ieee802_11_parse_elems_full() stores elems->tim = elem->data and elems->tim_len = elem->datalen (net/mac80211/parse.c), so the valid bytes are [tim, tim + tim_len).
When walking the encoded blocks the function passes the walker an end sentinel of (const u8 *)tim + tim_len + 2, i.e. two bytes past the end of the element. ieee80211_s1g_find_target_block() loops while (ptr + 1 <= end) and dereferences ptr (and the per-mode ieee80211_s1g_len_*() helpers read *ptr), so it can read up to two bytes beyond the TIM element -- an out-of-bounds read of adjacent skb/heap data when the TIM is the last element in the frame. The +2 appears to account for the element id/len header, but tim already points past that header at the element payload, so the addend is wrong.
Pass the correct element end, (const u8 *)tim + tim_len.
Which versions are affected by CVE-2026-74336?
How do I fix CVE-2026-74336?
Apply the vendor's patch.
Is CVE-2026-74336 being exploited?
There is no known exploitation of CVE-2026-74336 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-74336, DEBIAN-CVE-2026-74336, GHSA-4qq5-4vgc-w78g, UBUNTU-CVE-2026-74336.