CVE-2026-99278
ksmbd: limit sessions on each connection
What happened?
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: limit sessions on each connection
The pending setup limit only counts InProgress sessions. A client can complete authentication repeatedly and retain an unbounded number of Valid sessions on one connection.
Reserve a connection slot before allocating a session and retain a connection reference while authentication is in progress. The first SMB3 channel takes over that reservation; binding to another connection reserves one slot there. Reauthentication and authentication continuation reuse the existing reservation. Return slots on allocation or insertion failure, channel removal, and final session destruction.
Accept max_sessions_per_connection in reserved startup-request space and default to 64 when older tools leave it zero. Keep the request size and existing field offsets unchanged. Expose the configured limit in procfs. The existing connection limits bound the aggregate number of sessions without a separate global session allocation limit.
Affected software and versions
| Software | Version information | Fixed version |
|---|---|---|
| LinuxLinux | affected: d7fd1f98607f2cd358e583f9548bdf0173090a86 to < 94f8462fc9d5332bc54e91605003c17381e9171a; affected: d7fd1f98607f2cd358e583f9548bdf0173090a86 to < dc6aa1ba8b7fff8800ad9bf143f17d308e02ec68; affected: c99ea7855124ca1428a1e59c2b4590aaef34eacf; affected: 7.2.8 to < 7.3 | See vendor advisory |
| LinuxLinux | affected: 7.3; unaffected: 0 to < 7.3; unaffected: 7.3.2 to ≤ 7.3.*; unaffected: 7.4-rc1 to ≤ * | See vendor advisory |
Version information comes from the source record and can include unaffected products and exceptions. Distribution packages may contain backported fixes: an older upstream version alone does not prove a server is affected.
Is it being exploited?
This CVE was not listed in the CISA catalogue at our last retrieval. This does not establish that exploitation is absent.
How to respond
- Confirm the product, installed package version, and any configuration requirements in the vendor advisory.
- Follow the vendor’s remediation or workaround guidance in the references below. Structured fixed-version data is unavailable here; the publisher’s description may include a fix or workaround.
- Restart affected services if required, then verify the running version. Known exploitation may warrant investigation as well as patching.