CVE-2026-63830 (GCVE-0-2026-63830)

Vulnerability from cvelistv5 – Published: 2026-07-19 12:02 – Updated: 2026-07-20 13:40
VLAI
Title
net: skmsg: preserve sg.copy across SG transforms
Summary
In the Linux kernel, the following vulnerability has been resolved: net: skmsg: preserve sg.copy across SG transforms The sk_msg sg.copy bitmap is part of the scatterlist entry ownership state. A set bit tells sk_msg_compute_data_pointers() not to expose the entry through writable BPF ctx->data. This protects entries backed by pages that are not private to the sk_msg, such as splice-backed file page-cache pages. Several sk_msg transform paths move, copy, split, or compact msg->sg.data[] entries without moving the matching sg.copy bit. This can make an externally backed entry arrive at a new slot with a clear copy bit. A later SK_MSG verdict can then expose sg_virt(sge) as writable ctx->data and BPF stores can modify the original page cache. Keep sg.copy synchronized with sg.data[] whenever entries are transferred, shifted, split, or copied into a new sk_msg. Clear the bit when an entry is replaced by a newly allocated private page or freed. This covers the BPF pull/push/pop helpers, sk_msg_shift_left/right(), sk_msg_xfer(), and tls_split_open_record(), including the partial tail entry created during TLS open-record splitting.
Severity
9.4 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:L
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < 9bb86d8184b37503816150c4a6ad3c17dfdbe827 (git)
Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < 0eb4c16c4adb262763bda870a8ed38a1a9dec7ec (git)
Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < d22cc92bc41290e5783a72375e0843d9435f6001 (git)
Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < 1acdd14c0990dd1cd4b6534f00366d2e6dfce05f (git)
Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < 21ed9540a8e1906dfcbc1bb82ba9b4de4fa4bd6d (git)
Affected: d3b18ad31f93d0b6bae105c679018a1ba7daa9ca , < 406e8a651a7b854c41fecd5117bb282b3a6c2c6b (git)
Create a notification for this product.
Linux Linux Affected: 4.20
Unaffected: 0 , < 4.20 (semver)
Unaffected: 6.1.177 , ≤ 6.1.* (semver)
Unaffected: 6.6.144 , ≤ 6.6.* (semver)
Unaffected: 6.12.95 , ≤ 6.12.* (semver)
Unaffected: 6.18.38 , ≤ 6.18.* (semver)
Unaffected: 7.1.3 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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    "redhat_vex": {
      "aggregate_severity": "Important",
      "current_release_date": "2026-07-20T16:36:47+00:00",
      "cve": "CVE-2026-63830",
      "id": "CVE-2026-63830",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_affected": "246",
      "product_status:known_not_affected": "29",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: skmsg: preserve sg.copy across SG transforms",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-63830.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.


Detection rules are retrieved from Rulezet.