CVE-2026-46289 (GCVE-0-2026-46289)
Vulnerability from cvelistv5
Published
2026-06-08 15:46
Modified
2026-08-05 12:31
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: lib/scatterlist: fix length calculations in extract_kvec_to_sg Patch series "Fix bugs in extract_iter_to_sg()", v3. Fix bugs in the kvec and user variants of extract_iter_to_sg. This series is growing due to useful remarks made by sashiko.dev. The main bugs are: - The length for an sglist entry when extracting from a kvec can exceed the number of bytes in the page. This is obviously not intended. - When extracting a user buffer the sglist is temporarily used as a scratch buffer for extracted page pointers. If the sglist already contains some elements this scratch buffer could overlap with existing entries in the sglist. The series adds test cases to the kunit_iov_iter test that demonstrate all of these bugs. Additionally, there is a memory leak fix for the test itself. The bugs were orignally introduced into kernel v6.3 where the function lived in fs/netfs/iterator.c. It was later moved to lib/scatterlist.c in v6.5. Thus the actual fix is only marked for backports to v6.5+. This patch (of 5): When extracting from a kvec to a scatterlist, do not cross page boundaries. The required length was already calculated but not used as intended. Adjust the copied length if the loop runs out of sglist entries without extracting everything. While there, return immediately from extract_iter_to_sg if there are no sglist entries at all. A subsequent commit will add kunit test cases that demonstrate that the patch is necessary.
References
Impacted products
Vendor Product Version
Linux Linux Version: 0185846975339a5c348373aa450a977f5242366b
Version: 0185846975339a5c348373aa450a977f5242366b
Version: 0185846975339a5c348373aa450a977f5242366b
Version: 0185846975339a5c348373aa450a977f5242366b
Version: 0185846975339a5c348373aa450a977f5242366b
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlib/scatterlist: fix length calculations in extract_kvec_to_sg\n\nPatch series \"Fix bugs in extract_iter_to_sg()\", v3.\n\nFix bugs in the kvec and user variants of extract_iter_to_sg.  This series\nis growing due to useful remarks made by sashiko.dev.\n\nThe main bugs are:\n- The length for an sglist entry when extracting from\n  a kvec can exceed the number of bytes in the page. This\n  is obviously not intended.\n- When extracting a user buffer the sglist is temporarily\n  used as a scratch buffer for extracted page pointers.\n  If the sglist already contains some elements this scratch\n  buffer could overlap with existing entries in the sglist.\n\nThe series adds test cases to the kunit_iov_iter test that demonstrate all\nof these bugs.  Additionally, there is a memory leak fix for the test\nitself.\n\nThe bugs were orignally introduced into kernel v6.3 where the function\nlived in fs/netfs/iterator.c.  It was later moved to lib/scatterlist.c in\nv6.5.  Thus the actual fix is only marked for backports to v6.5+.\n\n\nThis patch (of 5):\n\nWhen extracting from a kvec to a scatterlist, do not cross page\nboundaries.  The required length was already calculated but not used as\nintended.\n\nAdjust the copied length if the loop runs out of sglist entries without\nextracting everything.\n\nWhile there, return immediately from extract_iter_to_sg if there are no\nsglist entries at all.\n\nA subsequent commit will add kunit test cases that demonstrate that the\npatch is necessary."
        }
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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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              "lang": "en",
              "value": "AV:N - The vulnerable `extract_kvec_to_sg()` is reached through `extract_iter_to_sg()` on the SMB3/CIFS client crypto path (`decrypt_raw_data()` \u2192 `crypt_message()` \u2192 `smb2_get_aead_req()`), which processes encrypted SMB traffic received over TCP/445 from a remote peer in the `cifsd` demultiplex thread.\nAC:L - When an `ITER_KVEC` iterator spans a page boundary, the bug deterministically sets inflated scatterlist lengths (`sg_set_page(..., len, off)` instead of `seg`); an attacker can choose I/O sizes and offsets to cross page boundaries without races or layout luck.\nPR:N - A malicious SMB server operator needs no local privileges on the victim host\u2014only an established SMB3 sealed session (common in enterprise NAS, cloud file shares, and domain-joined clients) to drive encrypted read/write traffic through the affected scatterlist construction.\nUI:N - No end-user interaction beyond normal automated SMB client operation is required once a share/session exists; the kernel processes attacker-supplied encrypted payloads on the network receive path without additional victim actions.\nS:U - Impact is kernel memory corruption and privilege escalation within the same kernel security domain; it does not cross VM, container, or IOMMU boundaries.\nC:H - Inflated scatter-gather lengths cause out-of-bounds reads past page boundaries when the malformed scatterlist is consumed by AEAD crypto/DMA, yielding arbitrary adjacent-kernel-memory disclosure primitives.\nI:H - The same corrupted scatterlist metadata directs crypto/DMA writes beyond the intended page, enabling out-of-bounds kernel writes and potential control-flow hijack from memory corruption.\nA:H - Scatterlist length corruption during in-kernel AEAD operations can cause kernel oops/panic or reliably destabilize the system; memory corruption bugs in this path carry high availability impact even before full exploitation."
            }
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      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:31:03.214Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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      "references": [
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          "url": "https://git.kernel.org/stable/c/3f17500e86d730c76db638bb3ae52f9b5e496c76"
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          "url": "https://git.kernel.org/stable/c/e5e22fc9963469e678c4f4bb38d26adcec107f1e"
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          "url": "https://git.kernel.org/stable/c/8fbba6829057979149d1b37d65690c037f3ddf4d"
        },
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        },
        {
          "url": "https://git.kernel.org/stable/c/07b7d66e65d9cfe6b9c2c34aa22cfcaac37a5c45"
        }
      ],
      "title": "lib/scatterlist: fix length calculations in extract_kvec_to_sg",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2026-46289",
    "datePublished": "2026-06-08T15:46:15.888Z",
    "dateReserved": "2026-05-13T15:03:33.110Z",
    "dateUpdated": "2026-08-05T12:31:03.214Z",
    "state": "PUBLISHED"
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