CVE-2026-98119 netfs: break unbuffered write when netfs_alloc_subrequest() fails
A local attacker can trigger a kernel crash via null pointer dereference in the netfs subsystem during unbuffered writes when memory allocation fails.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-98119?
CVE-2026-98119 is a medium-severity vulnerability in Linux kernel, published on 25 Sep 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:
netfs: break unbuffered write when netfs_alloc_subrequest() fails
syzbot reported a null-ptr-deref below [1] following a fault injection in netfs_alloc_subrequest(). [0]
When netfs_alloc_subrequest() fails, subreq is NULL. Later, netfs_prepare_write() tries to initialize members of subreq(e.g., source), the issue in [1] is triggered.
Let's handle the error of netfs_prepare_write() properly.
[0] FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 Call Trace: netfs_alloc_subrequest+0x116/0x3f0 netfs_prepare_write+0x76/0x7b0 netfs_unbuffered_write+0x75c/0x2020 netfs_unbuffered_write_iter_locked+0x7d6/0xa80 netfs_unbuffered_write_iter+0x442/0x720 v9fs_file_write_iter+0xbf/0x100 vfs_write+0x6ac/0x1050
[1] KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af] RIP: 0010:netfs_prepare_write+0xbc/0x7b0 fs/netfs/write_issue.c:173 Call Trace: netfs_unbuffered_write+0x75c/0x2020 fs/netfs/direct_write.c:111 netfs_unbuffered_write_iter_locked+0x7d6/0xa80 fs/netfs/direct_write.c:290 netfs_unbuffered_write_iter+0x442/0x720 fs/netfs/direct_write.c:382 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline]
Weakness: CWE-476
Which versions are affected by CVE-2026-98119?
It affects 1 product.
Products include Linux kernel.
How do I fix CVE-2026-98119?
Apply the vendor's patch.
Is CVE-2026-98119 being exploited?
There is no known exploitation of CVE-2026-98119 in the wild and no public exploit code.
Other vulnerabilities in Linux kernel
Sources
Also known as BELL-CVE-2026-98119, DEBIAN-CVE-2026-98119, GHSA-9vr4-4r2h-jqv2, UBUNTU-CVE-2026-98119.