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CVE-2026-53250 (GCVE-0-2026-53250)

Vulnerability from cvelistv5 – Published: 2026-06-25 08:39 – Updated: 2026-09-14 11:58
VLAI
Title
xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()
Summary
In the Linux kernel, the following vulnerability has been resolved: xsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata() The TX metadata area resides in the UMEM buffer which is memory-mapped and concurrently writable by userspace. In xsk_skb_metadata(), csum_start and csum_offset are read from shared memory for bounds validation, then read again for skb assignment. A malicious userspace application can race to overwrite these values between the two reads, bypassing the bounds check and causing out-of-bounds memory access during checksum computation in the transmit path. Fix this by reading csum_start and csum_offset into local variables once, then using the local copies for both validation and assignment. Note that other metadata fields (flags, launch_time) and the cached csum fields may be mutually inconsistent due to concurrent userspace writes, but this is benign: the only security-critical invariant is that each field's validated value is the same one used, which local caching guarantees.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 48eb03dd26304c24f03bdbb9382e89c8564e71df , < eb778aed8a9b2381668fcb1247ae4fa011224768 (git)
Affected: 48eb03dd26304c24f03bdbb9382e89c8564e71df , < 0dfe05b938435892875e07771170051346412df9 (git)
Affected: 48eb03dd26304c24f03bdbb9382e89c8564e71df , < bfdfd2706d5fb2cd496a1506e680daf979309c8b (git)
Affected: 48eb03dd26304c24f03bdbb9382e89c8564e71df , < 22ba97ea9cc1f63a0d0244fae38057ed452b6ac7 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.12.110 , ≤ 6.12.* (semver)
Unaffected: 6.18.36 , ≤ 6.18.* (semver)
Unaffected: 7.0.13 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
guessed Create a notification for this product.
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nxsk: cache csum_start/csum_offset to fix TOCTOU in xsk_skb_metadata()\n\nThe TX metadata area resides in the UMEM buffer which is memory-mapped\nand concurrently writable by userspace. In xsk_skb_metadata(),\ncsum_start and csum_offset are read from shared memory for bounds\nvalidation, then read again for skb assignment. A malicious userspace\napplication can race to overwrite these values between the two reads,\nbypassing the bounds check and causing out-of-bounds memory access\nduring checksum computation in the transmit path.\n\nFix this by reading csum_start and csum_offset into local variables\nonce, then using the local copies for both validation and assignment.\n\nNote that other metadata fields (flags, launch_time) and the cached\ncsum fields may be mutually inconsistent due to concurrent userspace\nwrites, but this is benign: the only security-critical invariant is\nthat each field\u0027s validated value is the same one used, which local\ncaching guarantees."
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    "redhat_vex": {
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      "current_release_date": "2026-08-13T16:50:23+00:00",
      "cve": "CVE-2026-53250",
      "id": "CVE-2026-53250",
      "initial_release_date": "2026-06-25T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: Linux kernel (xsk): Out-of-bounds memory access via TOCTOU race condition",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-53250.json",
      "version": "3"
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      "aggregate_severity": "important",
      "current_release_date": "2026-09-10T16:56:18Z",
      "cve": "CVE-2026-53250",
      "id": "CVE-2026-53250",
      "initial_release_date": "2026-06-26T02:08:39Z",
      "product_status:first_fixed": "2",
      "product_status:known_affected": "423",
      "product_status:known_not_affected": "279",
      "product_status:recommended": "281",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-53250",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-53250.json",
      "version": "16"
    }
  }
}



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  • 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.
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  • 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.


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