CVE-2026-43362 (GCVE-0-2026-43362)
Vulnerability from cvelistv5
Published
2026-05-08 14:21
Modified
2026-08-05 12:27
Severity ?
8.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix in-place encryption corruption in SMB2_write() SMB2_write() places write payload in iov[1..n] as part of rq_iov. smb3_init_transform_rq() pointer-shares rq_iov, so crypt_message() encrypts iov[1] in-place, replacing the original plaintext with ciphertext. On a replayable error, the retry sends the same iov[1] which now contains ciphertext instead of the original data, resulting in corruption. The corruption is most likely to be observed when connections are unstable, as reconnects trigger write retries that re-send the already-encrypted data. This affects SFU mknod, MF symlinks, etc. On kernels before 6.10 (prior to the netfs conversion), sync writes also used this path and were similarly affected. The async write path wasn't unaffected as it uses rq_iter which gets deep-copied. Fix by moving the write payload into rq_iter via iov_iter_kvec(), so smb3_init_transform_rq() deep-copies it before encryption.
References
Impacted products
Vendor Product Version
Linux Linux Version: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398
Version: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398
Version: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398
Version: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398
Version: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/smb/client/smb2pdu.c"
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          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
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              "version": "4.11"
            },
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              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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            {
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              "status": "unaffected",
              "version": "6.6.130",
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            },
            {
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              "status": "unaffected",
              "version": "6.12.78",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.19",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.19.*",
              "status": "unaffected",
              "version": "6.19.9",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.0",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.6.130",
                  "versionStartIncluding": "4.11",
                  "vulnerable": true
                },
                {
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                  "versionEndExcluding": "6.12.78",
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                {
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                  "vulnerable": true
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                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionEndExcluding": "7.0",
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                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix in-place encryption corruption in SMB2_write()\n\nSMB2_write() places write payload in iov[1..n] as part of rq_iov.\nsmb3_init_transform_rq() pointer-shares rq_iov, so crypt_message()\nencrypts iov[1] in-place, replacing the original plaintext with\nciphertext. On a replayable error, the retry sends the same iov[1]\nwhich now contains ciphertext instead of the original data,\nresulting in corruption.\n\nThe corruption is most likely to be observed when connections are\nunstable, as reconnects trigger write retries that re-send the\nalready-encrypted data.\n\nThis affects SFU mknod, MF symlinks, etc. On kernels before\n6.10 (prior to the netfs conversion), sync writes also used\nthis path and were similarly affected. The async write path\nwasn\u0027t unaffected as it uses rq_iter which gets deep-copied.\n\nFix by moving the write payload into rq_iter via iov_iter_kvec(),\nso smb3_init_transform_rq() deep-copies it before encryption."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The vulnerable SMB client write path is reached over an SMB3 network connection, and a malicious SMB server or network attacker able to force reconnects can trigger the retry after encryption.\nAC:L - The required conditions are straightforward: SMB3 encryption enabled, a write through `SMB2_write()`, and a replayable `-EAGAIN`/`-ECONNABORTED` error that the remote endpoint can plausibly induce by dropping/resetting the connection.\nPR:N - The attacker does not need privileges on the victim system; the attack can be mounted by the remote SMB endpoint or network adversary against a client that connects and writes to the share.\nUI:R - A victim system or user must mount/use the SMB share and perform writes, such as ordinary buffered writes on affected pre-6.10 kernels or symlink/SFU special-file operations on later affected kernels.\nS:U - The corruption occurs within the SMB client/filesystem write security context and does not cross a VM, sandbox, IOMMU, or comparable security boundary.\nC:N - The bug corrupts plaintext buffers into ciphertext and stores garbage on retry, but it does not provide a new information disclosure primitive or kernel memory read.\nI:H - The attacker can cause durable corruption of file contents written through the encrypted SMB client path, including ordinary file writes on affected pre-6.10 kernels, so high integrity impact is defensible.\nA:H - Repeated durable corruption of files being written to an encrypted SMB share can render application data or filesystem contents unusable, creating high availability impact in severe deployments."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-05T12:27:28.156Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/438e77435aee2894d5edf90be5c87004a57f6258"
        },
        {
          "url": "https://git.kernel.org/stable/c/52327268224fb9ccc7ecfbbdfdfff54b6e93c518"
        },
        {
          "url": "https://git.kernel.org/stable/c/92e64f1852f455f57d0850989e57c30d7fac7d95"
        },
        {
          "url": "https://git.kernel.org/stable/c/aea5e37388a080361110ab5790f57ae0af383650"
        },
        {
          "url": "https://git.kernel.org/stable/c/d78840a6a38d312dc1a51a65317bb67e46f0b929"
        }
      ],
      "title": "smb: client: fix in-place encryption corruption in SMB2_write()",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-43362",
    "datePublished": "2026-05-08T14:21:16.358Z",
    "dateReserved": "2026-05-01T14:12:56.005Z",
    "dateUpdated": "2026-08-05T12:27:28.156Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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