{
  "affected": [
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.1.180-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:13",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.100-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:14",
        "name": "linux"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "7.1.5-1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "ecosystem_specific": {
        "urgency": "not yet assigned"
      },
      "package": {
        "ecosystem": "Debian:12",
        "name": "linux-6.12"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "6.12.100-1~deb12u1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "details": "In the Linux kernel, the following vulnerability has been resolved:  ipv6: Fix null-ptr-deref in fib6_nh_mtu_change().  fib6_nh_mtu_change() re-fetches idev via __in6_dev_get(arg-\u003edev) and dereferences idev-\u003ecnf.mtu6 without a NULL check. addrconf_ifdown() clears dev-\u003eip6_ptr with RCU_INIT_POINTER() after rt6_disable_ip() has released tb6_lock, so the RA-driven MTU walk can observe a NULL idev and oops. The caller rt6_mtu_change_route() guards its own __in6_dev_get(), but this re-fetch is unguarded; nexthop-backed routes survive addrconf_ifdown()'s flush, so the walk still reaches it after ip6_ptr is nulled.  Return 0 when idev is NULL, matching rt6_mtu_change_route() and the fib6_mtu() fix in commit 5ad509c1fdad (\"ipv6: Fix null-ptr-deref in fib6_mtu().\").    Oops: general protection fault, ... KASAN: null-ptr-deref in range         [0x00000000000002a8-0x00000000000002af]   RIP: 0010:fib6_nh_mtu_change+0x203/0x990    rt6_mtu_change_route+0x141/0x1d0    __fib6_clean_all+0xd0/0x160    rt6_mtu_change+0xb4/0x100    ndisc_router_discovery+0x24b5/0x2cb0    icmpv6_rcv+0x12e9/0x1710    ipv6_rcv+0x39b/0x410",
  "id": "DEBIAN-CVE-2026-64538",
  "modified": "2026-09-09T08:47:28.891488104Z",
  "published": "2026-07-27T21:17:06.130Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://security-tracker.debian.org/tracker/CVE-2026-64538"
    }
  ],
  "upstream": [
    "CVE-2026-64538"
  ]
}