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CVE-2026-74406 (GCVE-0-2026-74406)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:59 – Updated: 2026-08-17 05:46
VLAI
Title
vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive().
Summary
In the Linux kernel, the following vulnerability has been resolved: vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive(). udp_tunnel_sock_release() could set sk->sk_user_data to NULL while vxlan_gro_prepare_receive() is running. Let's check if rcu_dereference_sk_user_data() is NULL after skb_gro_remcsum_init().
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: 5602c48cf87562c2f95b831d690631935e834295 , < 9c58c729d32e7cea5772cc44929c6cd61e5a31cd (git)
Affected: 5602c48cf87562c2f95b831d690631935e834295 , < f79c80f173fda9545b220c1f094b65fc06c252d0 (git)
Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 08f40c0d23c67c3aa4224c3311e134999c721fb4 (git)
Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 4a8cde6f7281ea2c4c290f9ad9923b3631defceb (git)
Affected: 5602c48cf87562c2f95b831d690631935e834295 , < ef44dac2a37f86eeae6b88ed10a6d60b35387dfd (git)
Affected: 5602c48cf87562c2f95b831d690631935e834295 , < 30a45c0bffdd62350261e2f2689fdba426a33578 (git)
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Linux Linux Affected: 4.7
Unaffected: 0 , < 4.7 (semver)
Unaffected: 6.1.178 , ≤ 6.1.* (semver)
Unaffected: 6.6.145 , ≤ 6.6.* (semver)
Unaffected: 6.12.97 , ≤ 6.12.* (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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{
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              "version": "7.1.5",
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              "value": "AV:N - The bug is in vxlan_gro_prepare_receive() on the UDP GRO receive path; remote VXLAN/UDP packets reach it via inet_gro_receive\u2192udp4_gro_receive\u2192udp_tunnel_gro_rcv\u2192vxlan_gro_receive during NAPI processing on internet/cloud overlay endpoints.\nAC:L - An attacker can reliably trigger the race by flooding VXLAN GRO packets while concurrently tearing down the VXLAN device (e.g., via CAP_NET_ADMIN in a user namespace); repeated attempts during orchestrated interface churn also make the timing window attacker-driven rather than purely environmental.\nPR:N - Exploitation requires only the ability to send crafted VXLAN UDP traffic to a listening tunnel port; no target credentials or local account are needed, and concurrent teardown can occur from normal administrative or automation activity rather than attacker-held privileges.\nUI:N - No victim interaction is required beyond the host already running a VXLAN interface; the attacker triggers the fault purely by sending network packets timed against interface teardown.\nS:U - Impact is a kernel fault in networking softirq context on the same host; it does not cross VM, container, or IOMMU security boundaries into another authority.\nC:H - The race can leave a stale vxlan_sock pointer after udp_tunnel_sock_release() frees sk_user_data; dereferencing vs-\u003eflags is a use-after-free read that can expose kernel heap contents and is treated as arbitrary read potential under conservative scoring.\nI:H - Use-after-free on the vxlan_sock object during GRO teardown can corrupt heap metadata or adjacent objects and be leveraged for control-flow hijacking, not merely a benign NULL check failure.\nA:H - A successful trigger causes a kernel NULL pointer dereference/oops in NAPI/softirq context (documented crash at vxlan_gro_prepare_receive), typically crashing or hanging the host and denying all services."
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    "dateReserved": "2026-08-15T05:44:03.892Z",
    "dateUpdated": "2026-08-17T05:46:49.365Z",
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-19T10:28:08+00:00",
      "cve": "CVE-2026-74406",
      "id": "CVE-2026-74406",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "184",
      "product_status:known_not_affected": "90",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: vxlan: Fix potential null-ptr-deref in vxlan_gro_prepare_receive()",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74406.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.