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CVE-2026-68476 (GCVE-0-2026-68476)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:51 – Updated: 2026-09-02 12:49
VLAI
Title
ipvs: reload ip header after head reallocation
Summary
In the Linux kernel, the following vulnerability has been resolved: ipvs: reload ip header after head reallocation __ip_vs_get_out_rt() calls skb_ensure_writable() which may reallocate skb->head.
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: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < 4f2d1151421520d7ae16ca8d367d0ca09f5dfbd7 (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < 657118cad620172dfd8f6ed5717fd75c0d1f7a5a (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < a10f5080afbed242640f2984328de25f84557da1 (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < ac6ac3d35bfc0ade9d17d354c84e503a946ebdab (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < e51687fc56c2e39ea6e9532925f1aabd4d529f61 (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < 3fb7edd2018bb1ad0a68157383d9b9dac33dd645 (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < ad1e14710b360bda087ebf9fb82460eb5ef775de (git)
Affected: 8d8e20e2d7bba8c50e64e0eca1cb83956f468e49 , < a2f57827bf7c695b8c72dc4511cae8e86582369d (git)
guessed Create a notification for this product.
Linux Linux Affected: 4.10
Unaffected: 0 , < 4.10 (semver)
Unaffected: 5.10.269 , ≤ 5.10.* (semver)
Unaffected: 5.15.220 , ≤ 5.15.* (semver)
Unaffected: 6.1.187 , ≤ 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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          "product": "Linux",
          "programFiles": [
            "net/netfilter/ipvs/ip_vs_xmit.c"
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              "version": "4.10"
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              "version": "0",
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            },
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              "status": "unaffected",
              "version": "5.10.269",
              "versionType": "semver"
            },
            {
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              "status": "unaffected",
              "version": "5.15.220",
              "versionType": "semver"
            },
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              "version": "6.1.187",
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            {
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              "version": "6.6.145",
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              "status": "unaffected",
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            },
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              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
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          "nodes": [
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                  "versionEndExcluding": "5.10.269",
                  "versionStartIncluding": "4.10",
                  "vulnerable": true
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                {
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                  "versionEndExcluding": "5.15.220",
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                  "vulnerable": true
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipvs: reload ip header after head reallocation\n\n__ip_vs_get_out_rt() calls skb_ensure_writable() which may\nreallocate skb-\u003ehead."
        }
      ],
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            "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"
          },
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              "value": "AV:N - The flaw is in ip_vs_bypass_xmit() on the IPVS netfilter receive path (NF_INET_LOCAL_IN/FORWARD); remote IPv4 packets to a configured virtual-server VIP reach ip_vs_in_hook() and ip_vs_leave() without local syscalls or ioctl.\nAC:L - Once cache_bypass is enabled on a fwmark IPVS service with no backend, an attacker can repeatedly send traffic to the VIP; cloned skbs (common with bridging, mirroring, or shared receive buffers) make skb_ensure_writable() reallocate skb-\u003ehead deterministically.\nPR:N - Exploitation requires only sending IP packets to the load balancer VIP; IPVS/cache_bypass configuration is an operator prerequisite on the target, not a Linux capability the remote attacker must hold.\nUI:N - No victim interaction is required; kernel processing of attacker-crafted network packets on the IPVS bypass transmit path alone triggers the stale header pointer use after skb head reallocation.\nS:U - Impact is kernel heap corruption and load-balancer compromise within the host kernel security domain; it does not cross VM, container, or IOMMU boundaries to another security authority.\nC:H - After pskb_expand_head() frees the old skb-\u003ehead, ip_send_check() uses the stale iph pointer and ip_fast_csum() reads attacker-influenced bytes from freed kmalloc memory, a classic use-after-free information disclosure primitive.\nI:H - ip_send_check() writes through the stale iph pointer (zeroing and updating the checksum field) into freed/reallocated slab memory, enabling heap corruption and potential arbitrary kernel write or control-flow hijack primitives.\nA:H - Writing and reading through a stale IP header pointer after skb head reallocation can corrupt adjacent kernel heap objects or dereference freed memory, causing kernel oops, panic, or hang and repeatable denial of service."
            }
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        {
          "url": "https://git.kernel.org/stable/c/a2f57827bf7c695b8c72dc4511cae8e86582369d"
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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.

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.