# CVE-2026-98801: net: restrict SO_RESERVE_MEM to TCP sockets and cap max value

> A local attacker can trigger integer overflows and memory corruption in the Linux kernel via SO_RESERVE_MEM, potentially causing denial of service or privilege escalation.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Oct 2026
- **Updated:** 19 Oct 2026
- **Also known as:** AZL-109077, BELL-CVE-2026-98801, DEBIAN-CVE-2026-98801, GHSA-4vp5-jwr6-3q9m, UBUNTU-CVE-2026-98801

## What is CVE-2026-98801?

CVE-2026-98801 is a vulnerability in Linux, published on 18 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.

### Official 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).

## Which versions are affected by CVE-2026-98801?


## How do I fix CVE-2026-98801?

Apply the vendor's patch.

## Is CVE-2026-98801 being exploited?

There is no known exploitation of CVE-2026-98801 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-98801 and fix it if it is affected.

What it is: CVE-2026-98801 is a vulnerability in Linux, published on 18 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-98801 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-98801/ (Markdown: https://insights.sbomify.com/CVE-2026-98801/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-98801
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-98801
- OSV: https://osv.dev/vulnerability/CVE-2026-98801

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-98801/
Summaries are generated and may contain mistakes; the official description above is the record.