UBUNTU-CVE-2026-74336: Low severity ubuntu/linux-hwe-edge vulnerability
In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: bound S1G TIM PVB walk to the TIM element ieee80211s1gchecktim() parses the S1G Partial Virtual Bitmap (PVB) of a received TIM element. The TIM is handed in as the element payload: ieee80211parseelemsfull() stores elems->tim = elem->data and elems->timlen = elem->datalen (net/mac80211/parse.c), so the valid bytes are [tim, tim + timlen). When walking the encoded blocks the function passes the walker an end sentinel of (const u8 )tim + timlen + 2, i.e. two bytes past the end of the element. ieee80211s1gfindtargetblock() loops while (ptr + 1 <= end) and dereferences ptr (and the per-mode ieee80211s1glen() 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 + timlen.
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
Upgrade
ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
Upgrade
ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
Upgrade
ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
Upgrade
ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
Upgrade
ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
Upgrade
ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
Upgrade
ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
Upgrade
ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
Upgrade
ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
Upgrade
ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
Upgrade
ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
Upgrade
ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
Upgrade
ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
Upgrade
ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
Upgrade
ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
Upgrade
ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
Upgrade
ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Compensating control
In ieee80211_s1g_check_tim(), pass the TIM element end as (const u8 *)tim + tim_len to ieee80211_s1g_find_target_block(), instead of (const u8 *)tim + tim_len + 2, so PVB walking cannot read beyond the element.
Event History
Frequently Asked Questions
What systems are exposed to this issue?
Systems using the listed Ubuntu Linux kernel packages are exposed when mac80211 processes received S1G TIM elements. The out-of-bounds read occurs when the TIM is the last element in the received frame, allowing the parser to read adjacent skb or heap data.
What does an attacker need to trigger the flaw?
An attacker needs to provide a received frame containing an S1G TIM with encoded PVB blocks that cause the parser's walk to reach the incorrectly extended end boundary. The vulnerable code can then read up to two bytes beyond the TIM element payload.