CVE-2026-74433 (GCVE-0-2026-74433)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:59 – Updated: 2026-08-17 05:47
VLAI
Title
rxrpc: Fix UAF in rxgk_issue_challenge()
Summary
In the Linux kernel, the following vulnerability has been resolved: rxrpc: Fix UAF in rxgk_issue_challenge() Fix rxgk_issue_challenge() to free the page containing the challenge content after invoking the tracepoint as the whdr passed to the tracepoint points into the page just freed.
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a , < 844b8525ce503405c462ad67f750bec648720397 (git)
Affected: 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a , < 83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8 (git)
Affected: 9d1d2b59341f58126a69b51f9f5f8ccb9f12e54a , < 107a4cb0d47e735830f852d83970d5c81f8e1e08 (git)
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Linux Linux Affected: 6.16
Unaffected: 0 , < 6.16 (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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{
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      "affected": [
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/rxgk.c"
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              "versionType": "original_commit_for_fix"
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      "metrics": [
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            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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          "scenarios": [
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              "lang": "en",
              "value": "AV:N - The bug is in rxgk_issue_challenge() on the RxRPC server path reached when a remote UDP RxRPC DATA packet starts a new call; packets enter via rxrpc_encap_rcv() and the I/O thread, then conn_event processing issues an RxGK challenge during the pre-auth handshake on internet-facing AFS/RxGK servers.\nAC:L - Once an RxGK-enabled AFS kernel server is reachable, an attacker can reliably trigger rxgk_issue_challenge() by sending a valid incoming DATA packet with security index YFS-RxGK; the UAF is deterministic on each successful challenge transmission and does not depend on winning a race.\nPR:N - The vulnerable code runs during initial server-side connection setup before client credentials are verified: an unauthenticated remote peer that can reach the RxRPC UDP port can force challenge issuance without any local account, capability, or namespace privilege on the target.\nUI:N - Exploitation requires only network packets to the RxRPC listener; no victim user action such as opening files, mounting AFS, or enabling tracing is needed for the server to automatically enter the challenging path and hit the bug.\nS:U - Impact is confined to kernel memory integrity and availability on the AFS/RxRPC server host; it does not by itself cross a VM, container, or IOMMU security boundary, though it may enable local privilege escalation on that host.\nC:H - This is a use-after-free: __free_page() releases the challenge buffer before trace_rxrpc_tx_packet() dereferences whdr pointing into that page, enabling reads of freed slab/page memory and potential disclosure of kernel heap contents exploitable for KASLR bypass.\nI:H - UAF on the challenge transmit path can be leveraged with heap grooming to obtain controlled reuse of the freed page and build arbitrary kernel write or control-flow hijack primitives, not merely a bounded protocol corruption.\nA:H - Reading or reusing freed kernel pages during challenge handling can provoke kernel oops/panic or wedged RxRPC/AFS service state; repeated remote triggering of the handshake can deny availability of the file service even without full exploitation."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:47:07.711Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/844b8525ce503405c462ad67f750bec648720397"
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        {
          "url": "https://git.kernel.org/stable/c/83bb0ed050e2ad9453d8ef50e4d6e624eac6eed8"
        },
        {
          "url": "https://git.kernel.org/stable/c/107a4cb0d47e735830f852d83970d5c81f8e1e08"
        }
      ],
      "title": "rxrpc: Fix UAF in rxgk_issue_challenge()",
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74433",
    "datePublished": "2026-08-15T05:59:32.823Z",
    "dateReserved": "2026-08-15T05:44:03.896Z",
    "dateUpdated": "2026-08-17T05:47:07.711Z",
    "state": "PUBLISHED"
  },
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  }
}



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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.


Detection rules are retrieved from Rulezet.