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CVE-2026-98420— ksmbd: follow SMB2 session expiration semantics

Quick assessment

Affected
Linux Linux
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

在 Linux 内核中，已修复以下漏洞： ksmbd：遵循 SMB2 会话过期语义 函数存在缺陷：当客户端发起新的 （会话建立）请求时，无论之前存在的会话是否有效，只要该会话已闲置超过十秒，就会被销毁。这混淆了“会话空闲时间”（Session.IdleTime）与“会话过期时间”（Session.ExpirationTime）的概念。 Windows 客户端可以在现有连接上创建额外的已认证会话，因此过早删除旧会话会导致其树连接（tree connects）失效，从而使映射驱动器出现 错误。 根据会话过期规则，服务器

AI Predicted 5.3 Difficulty: Easy EPSS 0.24% · P14

Affected Version Matrix 14

VendorProduct Version RangeStatus
Linux Linux ea174a91893956450510945a0c5d1a10b5323656< c99ea7855124ca1428a1e59c2b4590aaef34eacf affected
ea174a91893956450510945a0c5d1a10b5323656< d7fd1f98607f2cd358e583f9548bdf0173090a86 affected
a6a9601ba995d0fec635324cb9fd8d14f9bea14e affected
1fc8a2b14ef5223f8e0b95faba2ee0a6e4d0f99d affected
750a2d772e9d9ff377fd32e3b6797bf2cd847a7a affected
6775ee7ef4b37c521aa4cf3730f54554c4875542 affected
5.15.145< 5.16 affected
6.1.29< 6.2 affected
… +6 more rows
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I. Basic Information for CVE-2026-98420

Vulnerability Information
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Vulnerability Title
ksmbd: follow SMB2 session expiration semantics
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
N/A
Source: CVE Program / CVE List V5
Vulnerability Type
N/A
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
Linux Linux ea174a91893956450510945a0c5d1a10b5323656 ~ c99ea7855124ca1428a1e59c2b4590aaef34eacf -
Linux Linux 6.4 -

II. Public POCs for CVE-2026-98420

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III. Intelligence Information for CVE-2026-98420

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Other References for CVE-2026-98420 (2)

Same Patch Batch · Linux · 2026-10-14 · 46 CVEs total

CVE-2026-98398 locking/lockdep: Invalidate stale class_cache entries for zapped classes
CVE-2026-98396 powerpc: Do not restore KUAP in arch_exit_to_user_mode_prepare()
CVE-2026-98393 net: ipv4: Fix UDP length overflow with PMTU discover and big MTU
CVE-2026-98391 drm/xe: Guard page-fault worker with runtime PM check
CVE-2026-98389 drm/amdgpu: skip gfx switch_power_profile during GPU reset
CVE-2026-98388 exec: do_close_on_exec() before taking exec_update_lock
CVE-2026-98387 s390/crypto: Fix skcipher_walk return code handling in aes_s390
CVE-2026-98386 scsi: qla2xxx: Use memset_io() to clear QLAFX00 request ring slot
CVE-2026-98390 x86/amd_node: Avoid divide by zero on virtualized systems
CVE-2026-98397 platform/x86: x86-android-tablets: hold device reference for secondary fwnode teardown
CVE-2026-98395 powerpc/entry: Fix irq_soft_mask corruption on replayed interrupt exit
CVE-2026-98399 s390/ipl: Fix NULL deref in dump_reipl without re-IPL parm block
CVE-2026-98400 s390/ipl: Fix NULL deref in kdump without re-IPL parm block
CVE-2026-98402 net: icmp: avoid invalid transport header access in icmp_send tracepoint
CVE-2026-98401 net: iptunnel: fix stale transport header during tunnel decapsulation
CVE-2026-98403 s390/boot: Avoid IPL parameter append past command line
CVE-2026-98404 drm/virtio: Fix a NULL vs ERR_PTR() bug in virtio_gpu_user_framebuffer_create()
CVE-2026-98405 smb: client: fix missing iov bounds check in parse_posix_sids()
CVE-2026-98406 wifi: mac80211: avoid WARN in set_bitrate_mask when sdata not in driver
CVE-2026-98408 watchdog: rzv2h: Avoid division by zero

Showing top 20 of 46 CVEs. View all on vendor page &rarr; →

IV. Related Vulnerabilities

Same product: Linux
Same vendor: Linux

V. Comments for CVE-2026-98420

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