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pppoatm: ensure a writable skb header and linear data

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: pppoatm: ensure a writable skb header and linear data In pppoatm_send(), LLC encapsulation checks whether there is sufficient headroom for the 4-byte LLC header, but does not ensure that the skb header is writable. Normal transmit packets passing through ppp_start_xmit() have their header unshared via skb_cow_head(). However, packets can also reach pppoatm_send() via PPP channel bridging (PPPIOCBRIDGECHAN) without going through ppp_start_xmit(). Use skb_cow_head() to ensure both sufficient headroom and a writable header before pushing the LLC header. While at it: - Call pskb_may_pull(skb, 1) before inspecting skb->data[0] to prevent out-of-bounds reads on zero-length or non-linear frames (e.g. from bridging). - Defer SC_COMP_PROT protocol compression until after pppoatm_may_send() succeeds. This eliminates the temporary skb allocation on admission failure and completely removes the fragile "undo" heuristic at the nospace label, avoiding any risk of reading uninitialized headroom or performing an unbalanced skb_push().

Announced Source revision 1
Original source ↗

CVE-2026-98287

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-2026-98287

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": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "208ccc4d08b1897451e9ba01c016bf93ff107966",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "e6cd1bba7d113c15c00ac63671213a096fe4d686",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "ffc448eb54f5ba80d4212c1e870cdb92b0f709fa",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "8e66c5969acd859ba72fb0a7fa895623fc1b3769",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "e2f5529b0016db7d34f411408607f5cf395a542e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "30992fe39e65589ed8e000425e088fa74994b811",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "4cf476ced45d7f12df30a68e833b263e7a2202d1",
        "lessThan": "ecc7253683a3c55caa868ce0ee530fcb0044bd3c",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/atm/pppoatm.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "5.11"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "5.11",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.15.222",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.189",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.158",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.112",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.54",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "7.2.8",
        "versionType": "semver",
        "lessThanOrEqual": "7.2.*"
      },
      {
        "status": "unaffected",
        "version": "7.3",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/atm/pppoatm.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-98287

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#38365 · Revision 1
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Publisher date
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