CVE-2026-72393 (GCVE-0-2026-72393)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
eth: fbnic: don't cache shinfo across skb realloc
Summary
In the Linux kernel, the following vulnerability has been resolved: eth: fbnic: don't cache shinfo across skb realloc fbnic_tx_lso() calls skb_cow_head() which may reallocate the skb including the shared info. We can't use the pointer calculated before the call. BUG: KASAN: slab-use-after-free in fbnic_tx_lso.isra.0+0x668/0x8e0 Read of size 4 at addr ff110000262edd98 by task swapper/5/0 Call Trace: fbnic_tx_lso.isra.0+0x668/0x8e0 fbnic_xmit_frame+0x622/0xba0 dev_hard_start_xmit+0xf4/0x620 Allocated by task 8653: __alloc_skb+0x11e/0x5f0 alloc_skb_with_frags+0xcc/0x6c0 sock_alloc_send_pskb+0x327/0x3f0 __ip_append_data+0x188b/0x47a0 ip_make_skb+0x24a/0x300 udp_sendmsg+0x14d2/0x21e0 Freed by task 0: kfree+0x123/0x5a0 pskb_expand_head+0x36c/0xfa0 fbnic_tx_lso.isra.0+0x500/0x8e0 fbnic_xmit_frame+0x622/0xba0 dev_hard_start_xmit+0xf4/0x620 sch_direct_xmit+0x25b/0x1100 The buggy address belongs to the object at ff110000262edc40 which belongs to the cache skbuff_small_head of size 640 The buggy address is located 344 bytes inside of freed 640-byte region [ff110000262edc40, ff110000262ede
Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: b0b0f52042acb324cd39fbefb2b1ae83af8f8ae1 , < 83df3e2594cd78aa40b1246a19879abb4891945b (git)
Affected: b0b0f52042acb324cd39fbefb2b1ae83af8f8ae1 , < 21f304c2aae46625e050c28d979f4b9d83faa85e (git)
Affected: b0b0f52042acb324cd39fbefb2b1ae83af8f8ae1 , < 62b68b774f06bf52e329f254f0199bc43d350ccf (git)
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Linux Linux Affected: 6.15
Unaffected: 0 , < 6.15 (semver)
Unaffected: 6.18.40 , ≤ 6.18.* (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/meta/fbnic/fbnic_txrx.c"
          ],
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              "versionType": "git"
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              "status": "affected",
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              "versionType": "git"
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          "product": "Linux",
          "programFiles": [
            "drivers/net/ethernet/meta/fbnic/fbnic_txrx.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.15"
            },
            {
              "lessThan": "6.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
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              "versionType": "semver"
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              "version": "7.1.5",
              "versionType": "semver"
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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          "nodes": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.40",
                  "versionStartIncluding": "6.15",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.5",
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              "operator": "OR"
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\neth: fbnic: don\u0027t cache shinfo across skb realloc\n\nfbnic_tx_lso() calls skb_cow_head() which may reallocate the skb\nincluding the shared info. We can\u0027t use the pointer calculated\nbefore the call.\n\n    BUG: KASAN: slab-use-after-free in fbnic_tx_lso.isra.0+0x668/0x8e0\n    Read of size 4 at addr ff110000262edd98 by task swapper/5/0\n    Call Trace:\n     fbnic_tx_lso.isra.0+0x668/0x8e0\n     fbnic_xmit_frame+0x622/0xba0\n     dev_hard_start_xmit+0xf4/0x620\n\n    Allocated by task 8653:\n     __alloc_skb+0x11e/0x5f0\n     alloc_skb_with_frags+0xcc/0x6c0\n     sock_alloc_send_pskb+0x327/0x3f0\n     __ip_append_data+0x188b/0x47a0\n     ip_make_skb+0x24a/0x300\n     udp_sendmsg+0x14d2/0x21e0\n\n    Freed by task 0:\n     kfree+0x123/0x5a0\n     pskb_expand_head+0x36c/0xfa0\n     fbnic_tx_lso.isra.0+0x500/0x8e0\n     fbnic_xmit_frame+0x622/0xba0\n     dev_hard_start_xmit+0xf4/0x620\n     sch_direct_xmit+0x25b/0x1100\n\n    The buggy address belongs to the object at ff110000262edc40\n     which belongs to the cache skbuff_small_head of size 640\n    The buggy address is located 344 bytes inside of\n     freed 640-byte region [ff110000262edc40, ff110000262ede"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in fbnic_tx_lso on the outbound netdev path; KASAN shows udp_sendmsg\u2192ip_make_skb\u2192dev_hard_start_xmit. Remote peers can trigger GSO/USO/TSO transmits on internet-facing Meta hosts with fbnic (TCP responses or UDP USO), reaching the vulnerable driver without local access.\nAC:L - The USO selftest reliably reproduces the UAF when sending UDP_SEGMENT GSO skbs; attackers control MSS, payload size, and timing to force skb_cow_head/pskb_expand_head to reallocate the skb, making the stale shinfo dereference repeatable rather than dependent on uncontrollable state.\nPR:N - Triggering requires only standard unprivileged socket sendmsg with GSO/USO offload on a host using fbnic, or causing such outbound segmented traffic as an unauthenticated remote client; no CAP_NET_ADMIN, root, or special credentials are needed along the traced path.\nUI:N - Exploitation is fully attacker-driven through crafted network traffic or socket operations; no victim click, mount, or other voluntary action is required beyond normal always-on network service operation.\nS:U - Impact is kernel slab corruption and crash/privilege escalation within the host kernel security domain; it does not cross a VM/hypervisor or IOMMU boundary into a separate security authority.\nC:H - KASAN reports a slab use-after-free with a 4-byte read from freed skb_shared_info after pskb_expand_head; UAF of shinfo fields (gso_type, gso_size, gso_segs) enables heap grooming and arbitrary kernel memory disclosure.\nI:H - Use-after-free of skb_shared_info in the transmit LSO path is memory corruption in attacker-influenced heap objects; stale shinfo values drive metadata and checksum updates, enabling control of kernel data and potential code execution primitives.\nA:H - The reported KASAN slab-use-after-free in fbnic_tx_lso causes kernel oops/panic on transmit; repeated GSO/USO/TSO packets can crash or hang the system, denying availability on affected fbnic-equipped servers."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:43:37.508Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/83df3e2594cd78aa40b1246a19879abb4891945b"
        },
        {
          "url": "https://git.kernel.org/stable/c/21f304c2aae46625e050c28d979f4b9d83faa85e"
        },
        {
          "url": "https://git.kernel.org/stable/c/62b68b774f06bf52e329f254f0199bc43d350ccf"
        }
      ],
      "title": "eth: fbnic: don\u0027t cache shinfo across skb realloc",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-72393",
    "datePublished": "2026-08-15T05:56:21.081Z",
    "dateReserved": "2026-08-09T03:40:39.924Z",
    "dateUpdated": "2026-08-17T05:43:37.508Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
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      "date": "2026-08-17",
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      "percentile": "0.45334"
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  }
}



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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.

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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 patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


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