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CVE-2026-74425 (GCVE-0-2026-74425)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:59 – Updated: 2026-08-17 05:47
VLAI
Title
afs: handle CB.InitCallBackState3 requests without a server record
Summary
In the Linux kernel, the following vulnerability has been resolved: afs: handle CB.InitCallBackState3 requests without a server record The cache manager callback path now attaches the server record to an incoming call through the rxrpc peer's app data. That association is not guaranteed to exist for every callback request, and most callback handlers already tolerate that case. Make CB.InitCallBackState3 follow the same pattern by checking whether a server record was attached before using it. If the peer is not mapped to a server record, trace the request and ignore it, matching the existing behaviour for other unmatched callback requests. This keeps the callback handler consistent with the rest of the cache manager service and avoids depending on peer state that may not be available for a given request.
Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 39ba6af83a7f9dee3e6a7916f41a48bcbda54eba , < 42e3917cdbdc3d35e191c525687a6d5427f237fd (git)
Affected: 40e8b52fe8c8ab6920ea5f59c5469b6918cce624 , < cc848a080f7a6848dfeef441722419fdcbfe9b8d (git)
Affected: 40e8b52fe8c8ab6920ea5f59c5469b6918cce624 , < 0bd5f2786a878148190b4c7c259d01313d5f2357 (git)
Affected: 40e8b52fe8c8ab6920ea5f59c5469b6918cce624 , < f3cf725cd284b7912d5522babb44721bf38c8887 (git)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/afs/cmservice.c"
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                  "vulnerable": true
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                },
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                  "versionStartIncluding": "6.15",
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              ],
              "negate": false,
              "operator": "OR"
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          ]
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nafs: handle CB.InitCallBackState3 requests without a server record\n\nThe cache manager callback path now attaches the server record to an\nincoming call through the rxrpc peer\u0027s app data.  That association is\nnot guaranteed to exist for every callback request, and most callback\nhandlers already tolerate that case.\n\nMake CB.InitCallBackState3 follow the same pattern by checking whether a\nserver record was attached before using it.  If the peer is not mapped\nto a server record, trace the request and ignore it, matching the\nexisting behaviour for other unmatched callback requests.\n\nThis keeps the callback handler consistent with the rest of the cache\nmanager service and avoids depending on peer state that may not be\navailable for a given request."
        }
      ],
      "metrics": [
        {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in the AFS cache-manager callback handler reached from remote RXRPC/UDP traffic on the CM listener (port 7001). Packets are processed via rxrpc_new_incoming_call() -\u003e afs_deliver_cm_op_id() -\u003e afs_deliver_cb_init_call_back_state3() without any local syscall.\nAC:L - Once AFS is loaded, an attacker can reliably trigger the NULL server path by sending a CB.InitCallBackState3 (opcode 213) from an unmapped peer; call-\u003eserver is only set from rxrpc peer app data in afs_rx_new_call() and may legitimately be NULL.\nPR:N - Exploitation requires no Linux privileges on the victim. The callback socket accepts remote RXRPC connections without local capability checks, and incoming connections with security index 0 bypass the challenge handshake, so no authenticated local user is needed.\nUI:N - No victim user action is required beyond the system already running the AFS client module with its callback socket open; the crash is caused entirely by attacker-sent network packets.\nS:U - Impact is a kernel NULL pointer dereference and resulting oops/panic within kernel context. This is a standard kernel denial-of-service and does not cross a security boundary such as VM escape or sandbox breakout.\nC:N - The failure is a NULL pointer dereference in memcmp(call-\u003erequest, \u0026call-\u003eserver-\u003e_uuid, ...) when call-\u003eserver is NULL. This is a pure crash with no out-of-bounds read, use-after-free, or information disclosure primitive.\nI:N - The vulnerability does not modify kernel or user data; it dereferences a NULL server pointer during UUID comparison. There is no memory corruption, arbitrary write, or code execution primitive.\nA:H - Dereferencing call-\u003eserver when it is NULL causes a kernel fault in the AFS async RXRPC workqueue path, producing an oops or panic and denying all system availability until reboot."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:47:00.844Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/42e3917cdbdc3d35e191c525687a6d5427f237fd"
        },
        {
          "url": "https://git.kernel.org/stable/c/cc848a080f7a6848dfeef441722419fdcbfe9b8d"
        },
        {
          "url": "https://git.kernel.org/stable/c/0bd5f2786a878148190b4c7c259d01313d5f2357"
        },
        {
          "url": "https://git.kernel.org/stable/c/f3cf725cd284b7912d5522babb44721bf38c8887"
        }
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      "title": "afs: handle CB.InitCallBackState3 requests without a server record",
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  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74425",
    "datePublished": "2026-08-15T05:59:27.806Z",
    "dateReserved": "2026-08-15T05:44:03.894Z",
    "dateUpdated": "2026-08-17T05:47:00.844Z",
    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74425",
      "date": "2026-09-04",
      "epss": "0.0035",
      "percentile": "0.27962"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74425\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T06:22:44.590\",\"lastModified\":\"2026-08-17T06:19:37.997\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nafs: handle CB.InitCallBackState3 requests without a server record\\n\\nThe cache manager callback path now attaches the server record to an\\nincoming call through the rxrpc peer\u0027s app data.  That association is\\nnot guaranteed to exist for every callback request, and most callback\\nhandlers already tolerate that case.\\n\\nMake CB.InitCallBackState3 follow the same pattern by checking whether a\\nserver record was attached before using it.  If the peer is not mapped\\nto a server record, trace the request and ignore it, matching the\\nexisting behaviour for other unmatched callback requests.\\n\\nThis keeps the callback handler consistent with the rest of the cache\\nmanager service and avoids depending on peer state that may not be\\navailable for a given request.\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"fs/afs/cmservice.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"39ba6af83a7f9dee3e6a7916f41a48bcbda54eba\",\"lessThan\":\"42e3917cdbdc3d35e191c525687a6d5427f237fd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"40e8b52fe8c8ab6920ea5f59c5469b6918cce624\",\"lessThan\":\"cc848a080f7a6848dfeef441722419fdcbfe9b8d\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"40e8b52fe8c8ab6920ea5f59c5469b6918cce624\",\"lessThan\":\"0bd5f2786a878148190b4c7c259d01313d5f2357\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"40e8b52fe8c8ab6920ea5f59c5469b6918cce624\",\"lessThan\":\"f3cf725cd284b7912d5522babb44721bf38c8887\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"fs/afs/cmservice.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.15\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.15\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.18.40\",\"lessThanOrEqual\":\"6.18.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.5\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":7.5,\"baseSeverity\":\"HIGH\",\"attackVector\":\"NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":3.9,\"impactScore\":3.6}]},\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0bd5f2786a878148190b4c7c259d01313d5f2357\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/42e3917cdbdc3d35e191c525687a6d5427f237fd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/cc848a080f7a6848dfeef441722419fdcbfe9b8d\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"},{\"url\":\"https://git.kernel.org/stable/c/f3cf725cd284b7912d5522babb44721bf38c8887\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T22:26:49+00:00",
      "cve": "CVE-2026-74425",
      "id": "CVE-2026-74425",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "76",
      "product_status:known_not_affected": "198",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: afs: handle CB.InitCallBackState3 requests without a server record",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74425.json",
      "version": "3"
    }
  }
}



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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.
  • 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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