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CVE-2024-50086 (GCVE-0-2024-50086)

Vulnerability from cvelistv5 – Published: 2024-10-29 00:50 – Updated: 2026-08-05 11:41
VLAI
Title
ksmbd: fix user-after-free from session log off
Summary
In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix user-after-free from session log off There is racy issue between smb2 session log off and smb2 session setup. It will cause user-after-free from session log off. This add session_lock when setting SMB2_SESSION_EXPIRED and referece count to session struct not to free session while it is being used.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: total
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2025-04-25 14:30 UTC
CWE
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 0f62358ce85b2d4c949ef1b648be01b29cec667a (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < a9839c37fd813b432988f58a9d9dd59253d3eb2c (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 5511999e9615e4318e9142d23b29bd1597befc08 (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < ee371898b53a9b9b51c02d22a8c31bfb86d45f0d (git)
Affected: 0626e6641f6b467447c81dd7678a69c66f7746cf , < 7aa8804c0b67b3cb263a472d17f2cb50d7f1a930 (git)
guessed Create a notification for this product.
Linux Linux Affected: 5.15
Unaffected: 0 , < 5.15 (semver)
Unaffected: 5.15.171 , ≤ 5.15.* (semver)
Unaffected: 6.1.114 , ≤ 6.1.* (semver)
Unaffected: 6.6.58 , ≤ 6.6.* (semver)
Unaffected: 6.11.5 , ≤ 6.11.* (semver)
Unaffected: 6.12 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
Show details on NVD website
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ksmbd: fix user-after-free from session log off",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2024/cve-2024-50086.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CVE Program Container\", \"references\": [{\"url\": \"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html\"}], \"providerMetadata\": {\"orgId\": \"af854a3a-2127-422b-91ae-364da2661108\", \"shortName\": \"CVE\", \"dateUpdated\": \"2025-11-03T22:25:18.791Z\"}}, {\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"scope\": \"UNCHANGED\", \"version\": \"3.1\", \"baseScore\": 7.8, \"attackVector\": \"LOCAL\", \"baseSeverity\": \"HIGH\", \"vectorString\": \"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H\", \"integrityImpact\": \"HIGH\", \"userInteraction\": \"NONE\", \"attackComplexity\": \"LOW\", \"availabilityImpact\": \"HIGH\", \"privilegesRequired\": \"LOW\", \"confidentialityImpact\": \"HIGH\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2024-50086\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"total\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-04-25T14:30:09.987767Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-416\", \"description\": \"CWE-416 Use After Free\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-04-25T14:30:11.300Z\"}}], \"cna\": {\"title\": \"ksmbd: fix user-after-free from session log off\", \"metrics\": [{\"cvssV3_1\": {\"version\": \"3.1\", \"baseScore\": 9.8, \"baseSeverity\": \"CRITICAL\", \"vectorString\": \"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\"}, \"scenarios\": [{\"lang\": \"en\", \"value\": \"AV:N - ksmbd is the in-kernel SMB server processing attacker-supplied SMB2 PDUs on TCP/445 (or RDMA), so the entire race is driven by remote network traffic. No local access to the target is required.\\nAC:L - The attacker controls both sides of the race \\u2014 one pipelined SMB2 request holds the raw `work-\u003esess` pointer while a second concurrently issued SMB2_SESSION_SETUP drives `ksmbd_expire_session()` into `kfree(sess)` \\u2014 and each PDU is dispatched to a separate workqueue item, so the race can be replayed indefinitely and widened with compound/large requests.\\nPR:N - No credentials are needed: `__session_create()` leaves a session `SMB2_SESSION_IN_PROGRESS` and `smb2_sess_setup()`\u0027s error path marks it `SMB2_SESSION_EXPIRED`, both of which `ksmbd_expire_session()` frees, while the concurrent work item still dereferences `work-\u003esess` in `smb3_preauth_hash_rsp()`/`set_sign_rsp()` after `ksmbd_conn_unlock()`. The logoff variant needs only an ordinary (including guest-mapped) SMB session.\\nUI:N - The attacker triggers everything by sending SMB2 requests to the listening ksmbd server; no action by any local user or administrator is involved.\\nS:U - The corruption and its consequences stay within the kernel\u0027s own security authority on the SMB server host, with no crossing of a VM, sandbox, or IOMMU boundary.\\nC:H - After the free, `set_sign_rsp()` HMACs the response with `sess-\u003esmb3signingkey` read from reclaimed slab memory and returns the result to the attacker, and `sess-\u003efile_table`/`sess-\u003etree_conns` lookups on freed xarrays yield attacker-influenced pointers, enabling disclosure of arbitrary kernel memory.\\nI:H - `smb3_preauth_hash_rsp()` writes a 64-byte SHA-512 result through the `Preauth_HashValue` pointer read out of the freed object, giving a controlled kernel write once the slab is sprayed; the freed `file_table`/`tree_conns`/`user` fields additionally allow type confusion and control-flow hijacking.\\nA:H - Even without successful exploitation the use-after-free dereferences freed slab memory and corrupts the allocator, producing kernel oopses and panics that take down the SMB server host, and it can be retriggered at will.\"}]}], \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"0f62358ce85b2d4c949ef1b648be01b29cec667a\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"a9839c37fd813b432988f58a9d9dd59253d3eb2c\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"5511999e9615e4318e9142d23b29bd1597befc08\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"ee371898b53a9b9b51c02d22a8c31bfb86d45f0d\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"0626e6641f6b467447c81dd7678a69c66f7746cf\", \"lessThan\": \"7aa8804c0b67b3cb263a472d17f2cb50d7f1a930\", \"versionType\": \"git\"}], \"programFiles\": [\"fs/smb/server/mgmt/user_session.c\", \"fs/smb/server/mgmt/user_session.h\", \"fs/smb/server/server.c\", \"fs/smb/server/smb2pdu.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"5.15\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"5.15\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"5.15.171\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"5.15.*\"}, {\"status\": \"unaffected\", \"version\": \"6.1.114\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.1.*\"}, {\"status\": \"unaffected\", \"version\": \"6.6.58\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.6.*\"}, {\"status\": \"unaffected\", \"version\": \"6.11.5\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.11.*\"}, {\"status\": \"unaffected\", \"version\": \"6.12\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"fs/smb/server/mgmt/user_session.c\", \"fs/smb/server/mgmt/user_session.h\", \"fs/smb/server/server.c\", \"fs/smb/server/smb2pdu.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/0f62358ce85b2d4c949ef1b648be01b29cec667a\"}, {\"url\": \"https://git.kernel.org/stable/c/a9839c37fd813b432988f58a9d9dd59253d3eb2c\"}, {\"url\": \"https://git.kernel.org/stable/c/5511999e9615e4318e9142d23b29bd1597befc08\"}, {\"url\": \"https://git.kernel.org/stable/c/ee371898b53a9b9b51c02d22a8c31bfb86d45f0d\"}, {\"url\": \"https://git.kernel.org/stable/c/7aa8804c0b67b3cb263a472d17f2cb50d7f1a930\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nksmbd: fix user-after-free from session log off\\n\\nThere is racy issue between smb2 session log off and smb2 session setup.\\nIt will cause user-after-free from session log off.\\nThis add session_lock when setting SMB2_SESSION_EXPIRED and referece\\ncount to session struct not to free session while it is being used.\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"5.15.171\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.1.114\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.6.58\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.11.5\", \"versionStartIncluding\": \"5.15\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12\", \"versionStartIncluding\": \"5.15\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-08-05T11:41:31.690Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2024-50086\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-08-05T11:41:31.690Z\", \"dateReserved\": \"2024-10-21T19:36:19.942Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2024-10-29T00:50:29.284Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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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.
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  • 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.


Detection rules are retrieved from Rulezet.


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Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.