CVE-2026-64055 (GCVE-0-2026-64055)

Vulnerability from cvelistv5 – Published: 2026-07-19 15:39 – Updated: 2026-08-05 12:38
VLAI
Title
net: ethernet: cortina: Carry over frag counter
Summary
In the Linux kernel, the following vulnerability has been resolved: net: ethernet: cortina: Carry over frag counter The gmac_rx() NAPI poll function assembles packets in an SKB from a ring buffer. If the ring buffer gets completely emptied during a poll cycle, we exit gmac_rx(), but the packet is not yet completely assembled in the SKB, yet the fragment counter frag_nr is reset to zero on the next invocation. Solve this by making the RX fragment counter a part of the port struct, and carry it over between invocations. Reset the fragment counter only right after calling napi_gro_frags(), on error (after calling napi_free_frags()) or if stopping the port. Reset it in some place where not strictly necessary just to emphasize what is going on. This was found by Sashiko during normal patch review.
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
Linux Linux Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < df31e3b64455293df1ea89c7da7d5c9bfbcdd253 (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < 7af1fabdee744b7995fe01b30b77dfc397657cb5 (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < 75105fcf73f1ce7d9f769aaefec6e6d6645d5ac0 (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < 78cf08b3be47c28f07008a76c932bad7cdffa9d8 (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < 7123cf481e21b54eb6adc4cb0d8dc2876aeaee41 (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < c373b34877afea61c89e0dd2e38948c624249b9b (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < 46806096f35b8d3dfa2f321ddd77f597edcdb85f (git)
Affected: 4d5ae32f5e1e13f7f36d6439ec3257993b9f5b88 , < ebd8ec2b309e3a447851b456ccaf8fb39f3661e7 (git)
Create a notification for this product.
Linux Linux Affected: 4.16
Unaffected: 0 , < 4.16 (semver)
Unaffected: 5.10.258 , ≤ 5.10.* (semver)
Unaffected: 5.15.209 , ≤ 5.15.* (semver)
Unaffected: 6.1.175 , ≤ 6.1.* (semver)
Unaffected: 6.6.142 , ≤ 6.6.* (semver)
Unaffected: 6.12.92 , ≤ 6.12.* (semver)
Unaffected: 6.18.34 , ≤ 6.18.* (semver)
Unaffected: 7.0.11 , ≤ 7.0.* (semver)
Unaffected: 7.1 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethernet: cortina: Carry over frag counter\n\nThe gmac_rx() NAPI poll function assembles packets in an\nSKB from a ring buffer.\n\nIf the ring buffer gets completely emptied during a poll cycle,\nwe exit gmac_rx(), but the packet is not yet completely\nassembled in the SKB, yet the fragment counter frag_nr is\nreset to zero on the next invocation.\n\nSolve this by making the RX fragment counter a part of the\nport struct, and carry it over between invocations.\n\nReset the fragment counter only right after calling\nnapi_gro_frags(), on error (after calling napi_free_frags())\nor if stopping the port.\n\nReset it in some place where not strictly necessary just to\nemphasize what is going on.\n\nThis was found by Sashiko during normal patch review."
        }
      ],
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            "baseSeverity": "CRITICAL",
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            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:N - The bug is in the Cortina Gemini GMAC RX NAPI path (gmac_rx), which processes incoming Ethernet frames delivered by hardware DMA; a remote attacker on any routable network can send crafted multi-fragment frames to the device\u0027s NIC without local access.\nAC:L - An attacker controls frame size (jumbo frames exceeding the 2048-byte RX buffer fragment size) and traffic timing to drain the RX ring mid-packet across NAPI poll cycles, reliably reproducing the lost frag_nr condition without depending on uncontrollable system state.\nPR:N - Exploitation requires only the ability to send Ethernet frames to the target interface; no local account, kernel capability, or authentication on the victim system is needed.\nUI:N - Packet reception and NAPI processing are fully automatic; no victim user action such as mounting a filesystem or opening a file is required.\nS:U - The vulnerability corrupts kernel skb metadata in the network driver and affects only the kernel\u0027s own security domain; it does not cross a VM, container, or IOMMU boundary by itself.\nC:H - Resetting frag_nr to zero while rx_skb retains prior fragments causes skb_fill_page_desc to overwrite fragment slot 0, shrinks nr_frags while inflating skb-\u003elen, and can trigger out-of-bounds kernel reads when GRO and the network stack process the corrupted skb.\nI:H - The bug corrupts kernel heap skb fragment metadata (overwritten page descriptors, inconsistent nr_frags versus len), which is memory corruption in kernel structures that can be leveraged for arbitrary write or control-flow hijack primitives.\nA:H - Submitting a corrupted multi-fragment skb to napi_gro_frags and the upper network stack can cause kernel oops, BUG, or panic during fragment traversal, checksum, or GRO processing."
            }
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        "dateUpdated": "2026-08-05T12:38:44.658Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
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          "url": "https://git.kernel.org/stable/c/df31e3b64455293df1ea89c7da7d5c9bfbcdd253"
        },
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    "cveId": "CVE-2026-64055",
    "datePublished": "2026-07-19T15:39:37.077Z",
    "dateReserved": "2026-07-19T07:54:57.030Z",
    "dateUpdated": "2026-08-05T12:38:44.658Z",
    "state": "PUBLISHED"
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port.\\n\\nReset it in some place where not strictly necessary just to\\nemphasize what is going on.\\n\\nThis was found by Sashiko during normal patch 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    "redhat_vex": {
      "aggregate_severity": "None",
      "current_release_date": "2026-07-21T08:04:28+00:00",
      "cve": "CVE-2026-64055",
      "id": "CVE-2026-64055",
      "initial_release_date": "2026-07-19T00:00:00+00:00",
      "product_status:known_not_affected": "275",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: net: ethernet: cortina: Carry over frag counter",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64055.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-07-30T16:33:12Z",
      "cve": "CVE-2026-64055",
      "id": "CVE-2026-64055",
      "initial_release_date": "2026-07-21T13:00:29Z",
      "product_status:known_affected": "243",
      "product_status:known_not_affected": "53",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64055",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64055.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.