CVE-2026-98801: Linux kernel · net: restrict SO_RESERVE_MEM to TCP sockets and cap max value
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 6.9 High.
Data as of 28 Oct 2026, 01:28 UTC
CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu 26.04 LTSlinux-gkepkg:deb/ubuntu/linux-gke?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
Description
In the Linux kernel, the following vulnerability has been resolved: net: restrict SO_RESERVE_MEM to TCP sockets and cap max value Commit 2bb2f5fb21b0 ("net: add new socket option SO_RESERVE_MEM") and commit d00c8ee31729 ("net: fix possible NULL deref in sock_reserve_memory") only checked sk_has_account(sk), which is true for both TCP and UDP sockets. However, SO_RESERVE_MEM and sk_unused_reserved_mem() are currently only supported by TCP: - On UDP sockets, sk->sk_forward_alloc is protected by sk->sk_receive_queue.lock, whereas sock_reserve_memory() and sock_release_reserved_memory() only acquire lock_sock(sk). Concurrent UDP packet reception/release and setsockopt(SO_RESERVE_MEM) corrupt sk_forward_alloc and memcg accounting. - udp_rmem_release() reclaims excess sk_forward_alloc without accounting for sk_unused_reserved_mem(sk). Restrict sock_reserve_memory() to TCP sockets (sk_is_tcp(sk)) for now. Supporting SO_RESERVE_MEM for UDP (acquiring sk_receive_queue.lock and honoring sk_unused_reserved_mem() in udp_rmem_release()) can be done in a future net-next series if needed. In addition, reject val > SZ_1G with -EINVAL in sk_setsockopt(SO_RESERVE_MEM). Without an upper bound, values near INT_MAX cause sk_mem_pages(delta) and (pages << PAGE_SHIFT) to overflow 32-bit signed int, corrupting sk->sk_forward_alloc and sk->sk_reserved_mem. Using a page-aligned cap (SZ_1G) ensures that the page-rounded sk->sk_reserved_mem reported by getsockopt(SO_RESERVE_MEM) can always be passed back to setsockopt(SO_RESERVE_MEM).
References
- ubuntu.com/security/CVE-2026-98801 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-98801 (opens in a new tab)
- git.kernel.org/stable/c/5069ce898148bd799395c5a464e006cbb840f188 (opens in a new tab)
- git.kernel.org/stable/c/492e04f9a00f3cc88a1f6899417b10f3019a624e (opens in a new tab)
- git.kernel.org/stable/c/37e02c42a00be692c06343e11779aadc45f45971 (opens in a new tab)
- git.kernel.org/stable/c/a467b05b201b5c26be52ed3081992fa9c0387648 (opens in a new tab)