FKIE_CVE-2026-90160

Vulnerability from fkie_nvd - Published: 2026-09-17 17:17 - Updated: 2026-09-17 17:17
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: lwt_bpf: Restore reserved headroom after xmit program ip_finish_output2() expands an skb to LL_RESERVED_SPACE(dev) before LWT xmit. An LWT_XMIT BPF program can then modify the skb head and still return BPF_OK, so bpf_xmit() rechecks the remaining headroom before the skb continues to neighbour output. That recheck uses dst->dev->hard_header_len. This is not enough for the neighbour cached-header path: neigh_hh_output() copies the cached hardware header using the aligned hh_cache size, HH_DATA_MOD for short headers or HH_DATA_ALIGN(hh_len) otherwise. On Ethernet, hard_header_len is 14 but the cached copy needs 16 bytes. If an LWT_XMIT BPF program calls bpf_skb_change_head(skb, 1, 0), the skb can still have 15 bytes of headroom after the program. The existing check accepts that, after which neigh_hh_output() hits its headroom warning and drops the skb. Use LL_RESERVED_SPACE(dst->dev) in the post-BPF headroom check to match the reservation made before LWT xmit.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/lwt_bpf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "753e5cdcca5474d230d62bb3489e5168ab27c272",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "c488071c3441fa34f5a87cd6c12ce2cc6304f20e",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "a38c0eb447e2dd0120a2ebcdba470f9505ac8907",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "de2b2004e16f2930eb689175e2c1998b0a68d499",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "7d043e24520a273c362be5dd7d9c82796879a49b",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "7cf561843ed0ad57501892a65abb77957e6c800f",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "179a5b2171573d94a25c9aa8e1c9f9ac352ad316",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            },
            {
              "lessThan": "5fe7007aed9ad069b2bd77e5d0c875c64f5c0269",
              "status": "affected",
              "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/core/lwt_bpf.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.10"
            },
            {
              "lessThan": "4.10",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.270",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.221",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.188",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.157",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.110",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.52",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.6",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nlwt_bpf: Restore reserved headroom after xmit program\n\nip_finish_output2() expands an skb to LL_RESERVED_SPACE(dev) before LWT\nxmit. An LWT_XMIT BPF program can then modify the skb head and still\nreturn BPF_OK, so bpf_xmit() rechecks the remaining headroom before the\nskb continues to neighbour output.\n\nThat recheck uses dst-\u003edev-\u003ehard_header_len. This is not enough for the\nneighbour cached-header path: neigh_hh_output() copies the cached hardware\nheader using the aligned hh_cache size, HH_DATA_MOD for short headers or\nHH_DATA_ALIGN(hh_len) otherwise.\n\nOn Ethernet, hard_header_len is 14 but the cached copy needs 16 bytes. If\nan LWT_XMIT BPF program calls bpf_skb_change_head(skb, 1, 0), the skb can\nstill have 15 bytes of headroom after the program. The existing check\naccepts that, after which neigh_hh_output() hits its headroom warning and\ndrops the skb.\n\nUse LL_RESERVED_SPACE(dst-\u003edev) in the post-BPF headroom check to match\nthe reservation made before LWT xmit."
    }
  ],
  "id": "CVE-2026-90160",
  "lastModified": "2026-09-17T17:17:09.190",
  "metrics": {},
  "published": "2026-09-17T17:17:09.190",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/179a5b2171573d94a25c9aa8e1c9f9ac352ad316"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5fe7007aed9ad069b2bd77e5d0c875c64f5c0269"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/753e5cdcca5474d230d62bb3489e5168ab27c272"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7cf561843ed0ad57501892a65abb77957e6c800f"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/7d043e24520a273c362be5dd7d9c82796879a49b"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a38c0eb447e2dd0120a2ebcdba470f9505ac8907"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/c488071c3441fa34f5a87cd6c12ce2cc6304f20e"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/de2b2004e16f2930eb689175e2c1998b0a68d499"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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