CVE-2026-53366 (GCVE-0-2026-53366)

Vulnerability from cvelistv5 – Published: 2026-07-16 05:13 – Updated: 2026-08-17 04:50
VLAI
Title
ipv4: account for fraggap on the paged allocation path
Summary
In the Linux kernel, the following vulnerability has been resolved: ipv4: account for fraggap on the paged allocation path In __ip_append_data(), when the paged-allocation branch is taken, alloclen and pagedlen are computed as alloclen = fragheaderlen + transhdrlen; pagedlen = datalen - transhdrlen; datalen already includes fraggap, but the fraggap bytes carried over from the previous skb are copied into the new skb's linear area at offset transhdrlen by the subsequent skb_copy_and_csum_bits(). The linear area is therefore undersized by fraggap bytes while pagedlen is overstated by the same amount. The non-paged branch sets alloclen to fraglen, which already accounts for fraggap because datalen does. Bring the paged branch in line by adding fraggap to alloclen and subtracting it from pagedlen. After this adjustment, copy no longer collapses to -fraggap on the paged path, so remove the stale comment describing that old arithmetic.
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: 8eb77cc73977d88787b37c92831b1c242e035396 , < 5c6375bced6147ec2e460ee3b653f4860d5ecdc2 (git)
Affected: 8eb77cc73977d88787b37c92831b1c242e035396 , < ce494707a9c07f27c219ca67f3e138061f53d9b3 (git)
Affected: 8eb77cc73977d88787b37c92831b1c242e035396 , < a9c24eda24bd15f432e37824e6fc440977cb241c (git)
Affected: 8eb77cc73977d88787b37c92831b1c242e035396 , < 77798d7be6ef71e72fb6fc8a2901bf74ebc9706f (git)
Affected: 8eb77cc73977d88787b37c92831b1c242e035396 , < c04d9ece23deb9e26c19f9ca215e98b3295aa1bb (git)
Affected: 8eb77cc73977d88787b37c92831b1c242e035396 , < eca856950f7cb1a221e02b99d758409f2c5cec42 (git)
guessed Create a notification for this product.
Linux Linux Affected: 6.0
Unaffected: 0 , < 6.0 (semver)
Unaffected: 6.1.178 , ≤ 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 , ≤ * (original_commit_for_fix)
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              "value": "AV:L - The vulnerable code is reached while a local process constructs outgoing IPv4 UDP/raw/ping datagrams through sendmsg/splice/sendfile-style socket paths. I did not find a defensible received-packet or unauthenticated remote path that supplies the required cork/MSG_MORE-style fraggap conditions.\nAC:L - The attacker can choose UDP socket options/flags, payload sizes, corking/MSG_MORE behavior, and splice/zerocopy-style paged sends to reach the fraggap paged-allocation path. There is no race or external timing condition required.\nPR:L - A normal unprivileged local user can create IPv4 UDP sockets and use UDP_CORK/MSG_MORE/splice or related paged send paths; raw sockets are CAP_NET_RAW-gated but are not needed for the strongest local trigger. This is therefore basic local user privilege, not real administrator privilege.\nUI:N - No victim interaction is required once the attacker can run the local send/splice sequence. The vulnerable skb construction happens synchronously in the attacker-driven socket send path.\nS:U - The impact is within the same kernel security authority as the vulnerable IPv4 networking code. This is not a VM escape, IOMMU bypass, or cross-authority boundary violation.\nC:H - The bug under-allocates/accounting for the linear skb area and can copy attacker-controlled fraggap bytes past skb-\u003eend into trailing skb_shared_info metadata. Kernel memory corruption of this kind is reasonably capable of being developed into information disclosure, so the higher severity confidentiality value is appropriate.\nI:H - The copied fraggap bytes corrupt kernel skb metadata past the intended buffer boundary. This is an out-of-bounds write in kernel heap/networking structures and is scored as high integrity impact.\nA:H - The corrupted skb metadata can crash or destabilize the kernel networking stack, and related negative-copy accounting can also produce severe send-path failure behavior. Kernel crash or oops potential is high availability impact."
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    "redhat_vex": {
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      "cve": "CVE-2026-53366",
      "id": "CVE-2026-53366",
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      "product_status:fixed": "616",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv4: account for fraggap on the paged allocation path",
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      "version": "3"
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      "aggregate_severity": "important",
      "current_release_date": "2026-08-21T00:53:34Z",
      "cve": "CVE-2026-53366",
      "id": "CVE-2026-53366",
      "initial_release_date": "2026-07-21T13:07:21Z",
      "product_status:first_fixed": "55",
      "product_status:known_affected": "441",
      "product_status:known_not_affected": "167",
      "product_status:recommended": "455",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-53366",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-53366.json",
      "version": "18"
    }
  }
}



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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.
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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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