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GHSA-H7RP-R63V-FMFM

Vulnerability from github – Published: 2026-10-14 15:32 – Updated: 2026-10-14 15:32

Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98420"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-14T14:17:53Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: follow SMB2 session expiration semantics\n\nksmbd_session_register() destroys valid sessions after ten seconds of\ninactivity whenever a client starts another SessionSetup exchange. This\nconfuses Session.IdleTime with Session.ExpirationTime. Windows can create\nadditional authenticated sessions on an existing connection, so deleting\nthe older session invalidates its tree connects and makes mapped drives\nfail with STATUS_NETWORK_NAME_DELETED.\n\nThe session expiration rules require the server to change a valid session\nto expired only after its credential expiration time passes. A valid or\nexpired session otherwise keeps its connection from being scavenged.\nConnections that have not negotiated a dialect, have no sessions, or have\nonly InProgress sessions are disconnected after an implementation-specific\ntimeout. Use the Windows-compatible 45 second value and run the expiration\ncheck periodically for both TCP and SMB Direct.\n\nKeep zero as an infinite credential expiration time, and count each\nValid-to-Expired transition. Set expired sessions to InProgress when they\nreauthenticate. If authentication fails, remove the session from the\nglobal and per-connection tables immediately, including SMB3 multichannel\nconnections.\n\nRetain protection against abandoned SessionId-zero exchanges by allowing\nonly one InProgress authentication per connection. Additional exchanges\nfail with STATUS_INSUFFICIENT_RESOURCES, and stale InProgress sessions are\nreaped after the same 45 second setup timeout. This bounds the original\nunauthenticated memory-exhaustion path without evicting established\nsessions.",
  "id": "GHSA-h7rp-r63v-fmfm",
  "modified": "2026-10-14T15:32:21Z",
  "published": "2026-10-14T15:32:21Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98420"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c99ea7855124ca1428a1e59c2b4590aaef34eacf"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d7fd1f98607f2cd358e583f9548bdf0173090a86"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98420 (GCVE-0-2026-98420)

Vulnerability from cvelistv5 – Published: 2026-10-14 13:27 – Updated: 2026-10-14 13:27

Title

ksmbd: follow SMB2 session expiration semantics

Summary

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.

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6667 records in the last 180 days details

References

2 references

URL	Tags
https://git.kernel.org/stable/c/c99ea7855124ca142…
https://git.kernel.org/stable/c/d7fd1f98607f2cd35…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: ea174a91893956450510945a0c5d1a10b5323656 , < c99ea7855124ca1428a1e59c2b4590aaef34eacf (git) Affected: ea174a91893956450510945a0c5d1a10b5323656 , < d7fd1f98607f2cd358e583f9548bdf0173090a86 (git) Affected: a6a9601ba995d0fec635324cb9fd8d14f9bea14e (git) Affected: 1fc8a2b14ef5223f8e0b95faba2ee0a6e4d0f99d (git) Affected: 750a2d772e9d9ff377fd32e3b6797bf2cd847a7a (git) Affected: 6775ee7ef4b37c521aa4cf3730f54554c4875542 (git) Affected: 5.15.145 , < 5.16 (semver) Affected: 6.1.29 , < 6.2 (semver) Affected: 6.2.16 , < 6.3 (semver) Affected: 6.3.2 , < 6.4 (semver)
Linux	Linux	Affected: 6.4 Unaffected: 0 , < 6.4 (semver) Unaffected: 7.2.8 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)

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            "fs/smb/server/connection.c",
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            "fs/smb/server/mgmt/user_session.c",
            "fs/smb/server/mgmt/user_session.h",
            "fs/smb/server/proc.c",
            "fs/smb/server/server.c",
            "fs/smb/server/smb2pdu.c",
            "fs/smb/server/smb2pdu.h",
            "fs/smb/server/stats.h"
          ],
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            },
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              "versionType": "semver"
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            "fs/smb/server/mgmt/user_session.c",
            "fs/smb/server/mgmt/user_session.h",
            "fs/smb/server/proc.c",
            "fs/smb/server/server.c",
            "fs/smb/server/smb2pdu.c",
            "fs/smb/server/smb2pdu.h",
            "fs/smb/server/stats.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
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          "versions": [
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              "version": "6.4"
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              "versionType": "semver"
            },
            {
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              "status": "unaffected",
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        }
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          "url": "https://git.kernel.org/stable/c/d7fd1f98607f2cd358e583f9548bdf0173090a86"
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      ],
      "title": "ksmbd: follow SMB2 session expiration semantics",
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    "datePublished": "2026-10-14T13:27:49.599Z",
    "dateReserved": "2026-09-25T10:25:14.348Z",
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    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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