CVE-2026-43362 (GCVE-0-2026-43362)

Vulnerability from cvelistv5 – Published: 2026-05-08 14:21 – Updated: 2026-08-05 12:27
VLAI
Title
smb: client: fix in-place encryption corruption in SMB2_write()
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.
Severity
8.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 , < 438e77435aee2894d5edf90be5c87004a57f6258 (git)
Affected: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 , < 52327268224fb9ccc7ecfbbdfdfff54b6e93c518 (git)
Affected: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 , < 92e64f1852f455f57d0850989e57c30d7fac7d95 (git)
Affected: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 , < aea5e37388a080361110ab5790f57ae0af383650 (git)
Affected: 026e93dc0a3eefb0be060bcb9ecd8d7a7fd5c398 , < d78840a6a38d312dc1a51a65317bb67e46f0b929 (git)
Create a notification for this product.
Linux Linux Affected: 4.11
Unaffected: 0 , < 4.11 (semver)
Unaffected: 6.6.130 , ≤ 6.6.* (semver)
Unaffected: 6.12.78 , ≤ 6.12.* (semver)
Unaffected: 6.18.19 , ≤ 6.18.* (semver)
Unaffected: 6.19.9 , ≤ 6.19.* (semver)
Unaffected: 7.0 , ≤ * (original_commit_for_fix)
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          "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."
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              "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."
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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 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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-07-03T14:57:56+00:00",
      "cve": "CVE-2026-43362",
      "id": "CVE-2026-43362",
      "initial_release_date": "2026-05-08T00:00:00+00:00",
      "product_status:known_affected": "232",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: smb: client: fix in-place encryption corruption in SMB2_write()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43362.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "important",
      "current_release_date": "2026-07-19T17:38:41Z",
      "cve": "CVE-2026-43362",
      "id": "CVE-2026-43362",
      "initial_release_date": "2026-05-13T03:34:54Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "468",
      "product_status:known_not_affected": "122",
      "product_status:recommended": "325",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-43362",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-43362.json",
      "version": "20"
    }
  }
}



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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

Author Source Type Date Other

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.