GHSA-4HWH-2G43-5522

Vulnerability from github – Published: 2026-08-10 15:33 – Updated: 2026-08-19 18:32
VLAI
Details

In the Linux kernel, the following vulnerability has been resolved:

ila: reload IPv6 header after pskb_may_pull in checksum adjust

ila_csum_adjust_transport() caches ip6h = ipv6_hdr(skb) before calling pskb_may_pull(). On a non-linear skb whose transport header sits in a page fragment, pskb_may_pull() can call __pskb_pull_tail() / pskb_expand_head() and free the old skb head, leaving ip6h dangling; the following get_csum_diff(ip6h, p) then reads freed memory. ila_update_ipv6_locator() uses ip6h (and the iaddr derived from it) again after the csum-adjust call and additionally writes the new locator through that pointer.

Impact: a remote IPv6 packet routed through a configured ILA csum-adjust-transport route or receive-side mapping triggers a slab-use-after-free in ila_update_ipv6_locator() (KASAN). The route or mapping requires CAP_NET_ADMIN to configure, but trigger packets are unauthenticated once it exists.

Reload ip6h after each pskb_may_pull() in ila_csum_adjust_transport() before the csum-diff read. In ila_update_ipv6_locator() only the ILA_CSUM_ADJUST_TRANSPORT case pulls the skb, so reload ip6h and iaddr in that case alone before the destination-address write; the neutral-map modes never pull and keep their cached pointers.

Severity
9.8 (Critical)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-68127"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-10T13:19:57Z",
    "severity": "CRITICAL"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nila: reload IPv6 header after pskb_may_pull in checksum adjust\n\nila_csum_adjust_transport() caches ip6h = ipv6_hdr(skb) before calling\npskb_may_pull(). On a non-linear skb whose transport header sits in a page\nfragment, pskb_may_pull() can call __pskb_pull_tail() / pskb_expand_head()\nand free the old skb head, leaving ip6h dangling; the following\nget_csum_diff(ip6h, p) then reads freed memory. ila_update_ipv6_locator()\nuses ip6h (and the iaddr derived from it) again after the csum-adjust\ncall and additionally writes the new locator through that pointer.\n\nImpact: a remote IPv6 packet routed through a configured ILA\ncsum-adjust-transport route or receive-side mapping triggers a\nslab-use-after-free in ila_update_ipv6_locator() (KASAN). The route or\nmapping requires CAP_NET_ADMIN to configure, but trigger packets are\nunauthenticated once it exists.\n\nReload ip6h after each pskb_may_pull() in ila_csum_adjust_transport()\nbefore the csum-diff read. In ila_update_ipv6_locator() only the\nILA_CSUM_ADJUST_TRANSPORT case pulls the skb, so reload ip6h and iaddr in\nthat case alone before the destination-address write; the neutral-map\nmodes never pull and keep their cached pointers.",
  "id": "GHSA-4hwh-2g43-5522",
  "modified": "2026-08-19T18:32:06Z",
  "published": "2026-08-10T15:33:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-68127"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1eadcb43893b897ade85ac5bf5c618054bc3c655"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/472aba2603ca74c4f7722cb0c0296942b0776b8d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7097a0280b178237265681be66d1bef11d15894b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/896a9512d0d83c2a4b357e5585b7b62a8e3f95c1"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/92d3817649df2b0b6a008a686c8275c88d7ef594"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ba353caafb06ccee57b78d3254e3cebf1dea4a93"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c6a13ae00dab3a1a8c7cf2f843f0fc9e8d4b0ccc"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e451a904606c571f731ef7a06b3398619dce5300"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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