CVE-2026-98420 is a vulnerability in Linux Kernel
Published on October 14, 2026
ksmbd: follow SMB2 session expiration semantics
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: follow SMB2 session expiration semantics
ksmbd_session_register() destroys valid sessions after ten seconds of
inactivity whenever a client starts another SessionSetup exchange. This
confuses Session.IdleTime with Session.ExpirationTime. Windows can create
additional authenticated sessions on an existing connection, so deleting
the older session invalidates its tree connects and makes mapped drives
fail with STATUS_NETWORK_NAME_DELETED.
The session expiration rules require the server to change a valid session
to expired only after its credential expiration time passes. A valid or
expired session otherwise keeps its connection from being scavenged.
Connections that have not negotiated a dialect, have no sessions, or have
only InProgress sessions are disconnected after an implementation-specific
timeout. Use the Windows-compatible 45 second value and run the expiration
check periodically for both TCP and SMB Direct.
Keep zero as an infinite credential expiration time, and count each
Valid-to-Expired transition. Set expired sessions to InProgress when they
reauthenticate. If authentication fails, remove the session from the
global and per-connection tables immediately, including SMB3 multichannel
connections.
Retain protection against abandoned SessionId-zero exchanges by allowing
only one InProgress authentication per connection. Additional exchanges
fail with STATUS_INSUFFICIENT_RESOURCES, and stale InProgress sessions are
reaped after the same 45 second setup timeout. This bounds the original
unauthenticated memory-exhaustion path without evicting established
sessions.
Products Associated with CVE-2026-98420
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Affected Versions
Linux:- Version ea174a91893956450510945a0c5d1a10b5323656 and below c99ea7855124ca1428a1e59c2b4590aaef34eacf is affected.
- Version ea174a91893956450510945a0c5d1a10b5323656 and below d7fd1f98607f2cd358e583f9548bdf0173090a86 is affected.
- Version a6a9601ba995d0fec635324cb9fd8d14f9bea14e is affected.
- Version 1fc8a2b14ef5223f8e0b95faba2ee0a6e4d0f99d is affected.
- Version 750a2d772e9d9ff377fd32e3b6797bf2cd847a7a is affected.
- Version 6775ee7ef4b37c521aa4cf3730f54554c4875542 is affected.
- Version 5.15.145 and below 5.16 is affected.
- Version 6.1.29 and below 6.2 is affected.
- Version 6.2.16 and below 6.3 is affected.
- Version 6.3.2 and below 6.4 is affected.
- Version 6.4 is affected.
- Before 6.4 is unaffected.
- Version 7.2.8, <= 7.2.* is unaffected.
- Version 7.3-rc4, <= * is unaffected.