CVE-2026-90067

Status: UPDATED  |  Advisory ID: CVE-2026-90067

Key Details

Affected Products, Subsystems & Sectors

What to Know

In the Linux kernel, the following vulnerability has been resolved:

libceph: validate banner payload length

When parsing the Ceph messenger v2 protocol banner, the `payload_len` field

is decoded from the banner prefix. If a client sends a banner with a

`payload_len` of 0, the kernel sets up a 0-length socket read. This

violates an invariant in the state machine, triggering a warning in

`populate_in_iter()`:

------------[ cut here ]------------

!iov_iter_count(&con->v2.in_iter)

WARNING: net/ceph/messenger_v2.c:3129 at populate_in_iter

net/ceph/messenger_v2.c:3129 [inline], CPU#1: kworker/1:3/5070

WARNING: net/ceph/messenger_v2.c:3129 at ceph_con_v2_try_read+0x6634/0x6810

net/ceph/messenger_v2.c:3159, CPU#1: kworker/1:3/5070

...

Call Trace:

<TASK>

ceph_con_workfn+0x1f5/0x14a0 net/ceph/messenger.c:1575

process_one_work kernel/workqueue.c:3322 [inline]

process_scheduled_works+0xa8e/0x14e0 kernel/workqueue.c:3405

worker_thread+0xa47/0xfb0 kernel/workqueue.c:3486

kthread+0x388/0x470 kernel/kthread.c:436

ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158

ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

</TASK>

According to the msgr2 protocol specification, the banner payload is

expected to contain at least two 64-bit integers (`server_feat` and

`server_req_feat`). Therefore, `payload_len` must be at least 16 bytes.

Fix this by adding a check in `process_banner_prefix()` to reject a

`payload_len` smaller than 16 bytes. This prevents the 0-length read and

correctly aborts the connection with a protocol error. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References