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lwt_bpf: Restore reserved headroom after xmit program

Type: advisorySource: Official CVE List1 source record

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.

Announced Source revision 1
Original source ↗

CVE-2026-90160

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-90160

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "753e5cdcca5474d230d62bb3489e5168ab27c272",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "c488071c3441fa34f5a87cd6c12ce2cc6304f20e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "a38c0eb447e2dd0120a2ebcdba470f9505ac8907",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "de2b2004e16f2930eb689175e2c1998b0a68d499",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "7d043e24520a273c362be5dd7d9c82796879a49b",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "7cf561843ed0ad57501892a65abb77957e6c800f",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "179a5b2171573d94a25c9aa8e1c9f9ac352ad316",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "3a0af8fd61f90920f6fa04e4f1e9a6a73c1b4fd2",
        "lessThan": "5fe7007aed9ad069b2bd77e5d0c875c64f5c0269",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/core/lwt_bpf.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.10"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.10",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.270",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.221",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.188",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.157",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.110",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.52",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.6",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/core/lwt_bpf.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-90160

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#36548 · Revision 1
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