Vulnerability-Lookup

GHSA-P44R-FF57-RWR9

Vulnerability from github – Published: 2026-10-06 09:31 – Updated: 2026-10-06 09:31

Details

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

net: skbuff: do not leave stale header offsets after pskb_carve()

pskb_carve_inside_header() and pskb_carve_inside_nonlinear() remove the first bytes of a packet and reallocate skb->head.

All the headers that were present before the operation are gone, but both functions call skb_headers_offset_update(skb, 0), which is a no-op : skb->mac_header, skb->network_header, skb->transport_header and skb->csum_start keep their old values and now describe bytes which are no longer there.

Both helpers size the new head from the old skb_end_offset(), so the stale offsets still land inside the new allocation. They point past skb_tail_pointer() though, to bytes that were never initialized.

pskb_carve_inside_nonlinear() is the worst case, because it leaves a zombie skb with an empty linear part (skb->data == skb_tail_pointer(skb), skb_headlen(skb) == 0), while skb_mac_header_was_set() is still true and skb->mac_header is way ahead of skb->data.

The only user of pskb_extract() is rds_tcp_data_recv(), and the carved skb is queued on tinc->ti_skb_list. When the RDS incoming message is released, rds_tcp_inc_free() calls skb_queue_purge(), which frees the skbs with SKB_DROP_REASON_QUEUE_PURGE. This is visible from drop_monitor, which then tries to pull back to the (bogus) mac header :

skbuff: __skb_pull(len=234) skb len=6968 data_len=6968 headroom=0 headlen=0 tailroom=0 end-tail=384 mac=(234,14) mac_len=14 net=(248,40) trans=288 shinfo(txflags=0 nr_frags=1 gso(size=1428 type=16 segs=5)) csum(0x100120 start=288 offset=16 ip_summed=3 complete_sw=0 valid=1 level=0) hash(0x7b446c6c sw=0 l4=1) proto=0x86dd pkttype=0 iif=60 kernel BUG at ./include/linux/skbuff.h:2847!

Add skb_carve_reset_headers() to mark the mac and transport headers as not set, reset the network header, clear skb->mac_len, and drop a now meaningless CHECKSUM_PARTIAL (csum_start no longer describes anything).

Invalidate the inner offsets as well. Unlike mac_header and transport_header they have no "unset" sentinel, so a leftover non-zero value still looks like a real header. Zero skb->inner_mac_header, skb->inner_network_header, skb->inner_transport_header, skb->inner_protocol and skb->encapsulation, so that all the header state is invalidated in one place.

v2: fixed an inaccurate changelog. The stale offsets stay inside the new skb->head, which is never smaller than the old one, they simply point past skb_tail_pointer() to bytes that are gone. Thanks to Xuanqiang Luo for insisting on this. Also invalidate the inner header state, as suggested by the netdev AI review : https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260911114922.621937-1-edumazet%40google.com

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{
  "affected": [],
  "aliases": [
    "CVE-2026-98271"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-10-06T09:18:16Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: do not leave stale header offsets after pskb_carve()\n\npskb_carve_inside_header() and pskb_carve_inside_nonlinear() remove\nthe first bytes of a packet and reallocate skb-\u003ehead.\n\nAll the headers that were present before the operation are gone,\nbut both functions call skb_headers_offset_update(skb, 0), which\nis a no-op : skb-\u003emac_header, skb-\u003enetwork_header,\nskb-\u003etransport_header and skb-\u003ecsum_start keep their old values and\nnow describe bytes which are no longer there.\n\nBoth helpers size the new head from the old skb_end_offset(), so the\nstale offsets still land inside the new allocation. They point past\nskb_tail_pointer() though, to bytes that were never initialized.\n\npskb_carve_inside_nonlinear() is the worst case, because it leaves a\nzombie skb with an empty linear part (skb-\u003edata ==\nskb_tail_pointer(skb), skb_headlen(skb) == 0), while\nskb_mac_header_was_set() is still true and skb-\u003emac_header is way\nahead of skb-\u003edata.\n\nThe only user of pskb_extract() is rds_tcp_data_recv(), and the\ncarved skb is queued on tinc-\u003eti_skb_list. When the RDS incoming\nmessage is released, rds_tcp_inc_free() calls skb_queue_purge(),\nwhich frees the skbs with SKB_DROP_REASON_QUEUE_PURGE. This is\nvisible from drop_monitor, which then tries to pull back to the\n(bogus) mac header :\n\nskbuff: __skb_pull(len=234)\nskb len=6968 data_len=6968 headroom=0 headlen=0 tailroom=0\nend-tail=384 mac=(234,14) mac_len=14 net=(248,40) trans=288\nshinfo(txflags=0 nr_frags=1 gso(size=1428 type=16 segs=5))\ncsum(0x100120 start=288 offset=16 ip_summed=3 complete_sw=0 valid=1 level=0)\nhash(0x7b446c6c sw=0 l4=1) proto=0x86dd pkttype=0 iif=60\nkernel BUG at ./include/linux/skbuff.h:2847!\n\nAdd skb_carve_reset_headers() to mark the mac and transport headers\nas not set, reset the network header, clear skb-\u003emac_len, and drop\na now meaningless CHECKSUM_PARTIAL (csum_start no longer describes\nanything).\n\nInvalidate the inner offsets as well. Unlike mac_header and\ntransport_header they have no \"unset\" sentinel, so a leftover\nnon-zero value still looks like a real header. Zero\nskb-\u003einner_mac_header, skb-\u003einner_network_header,\nskb-\u003einner_transport_header, skb-\u003einner_protocol and\nskb-\u003eencapsulation, so that all the header state is invalidated in\none place.\n\nv2: fixed an inaccurate changelog. The stale offsets stay inside the\n    new skb-\u003ehead, which is never smaller than the old one, they\n    simply point past skb_tail_pointer() to bytes that are gone.\n    Thanks to Xuanqiang Luo for insisting on this.\n    Also invalidate the inner header state, as suggested by the\n    netdev AI review :\n    https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260911114922.621937-1-edumazet%40google.com",
  "id": "GHSA-p44r-ff57-rwr9",
  "modified": "2026-10-06T09:31:33Z",
  "published": "2026-10-06T09:31:33Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-98271"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/12929ed66a5166177ef5f06d3da81e4f99993e90"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/75e4a3e62531738c124c8555a626426fca29d392"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/bff8a8e53a6d290bc2777bde36d3cb6317b8463d"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}

CVE-2026-98271 (GCVE-0-2026-98271)

Vulnerability from cvelistv5 – Published: 2026-10-06 08:45 – Updated: 2026-10-06 08:45

Title

net: skbuff: do not leave stale header offsets after pskb_carve()

Summary

In the Linux kernel, the following vulnerability has been resolved: net: skbuff: do not leave stale header offsets after pskb_carve() pskb_carve_inside_header() and pskb_carve_inside_nonlinear() remove the first bytes of a packet and reallocate skb->head. All the headers that were present before the operation are gone, but both functions call skb_headers_offset_update(skb, 0), which is a no-op : skb->mac_header, skb->network_header, skb->transport_header and skb->csum_start keep their old values and now describe bytes which are no longer there. Both helpers size the new head from the old skb_end_offset(), so the stale offsets still land inside the new allocation. They point past skb_tail_pointer() though, to bytes that were never initialized. pskb_carve_inside_nonlinear() is the worst case, because it leaves a zombie skb with an empty linear part (skb->data == skb_tail_pointer(skb), skb_headlen(skb) == 0), while skb_mac_header_was_set() is still true and skb->mac_header is way ahead of skb->data. The only user of pskb_extract() is rds_tcp_data_recv(), and the carved skb is queued on tinc->ti_skb_list. When the RDS incoming message is released, rds_tcp_inc_free() calls skb_queue_purge(), which frees the skbs with SKB_DROP_REASON_QUEUE_PURGE. This is visible from drop_monitor, which then tries to pull back to the (bogus) mac header : skbuff: __skb_pull(len=234) skb len=6968 data_len=6968 headroom=0 headlen=0 tailroom=0 end-tail=384 mac=(234,14) mac_len=14 net=(248,40) trans=288 shinfo(txflags=0 nr_frags=1 gso(size=1428 type=16 segs=5)) csum(0x100120 start=288 offset=16 ip_summed=3 complete_sw=0 valid=1 level=0) hash(0x7b446c6c sw=0 l4=1) proto=0x86dd pkttype=0 iif=60 kernel BUG at ./include/linux/skbuff.h:2847! Add skb_carve_reset_headers() to mark the mac and transport headers as not set, reset the network header, clear skb->mac_len, and drop a now meaningless CHECKSUM_PARTIAL (csum_start no longer describes anything). Invalidate the inner offsets as well. Unlike mac_header and transport_header they have no "unset" sentinel, so a leftover non-zero value still looks like a real header. Zero skb->inner_mac_header, skb->inner_network_header, skb->inner_transport_header, skb->inner_protocol and skb->encapsulation, so that all the header state is invalidated in one place. v2: fixed an inaccurate changelog. The stale offsets stay inside the new skb->head, which is never smaller than the old one, they simply point past skb_tail_pointer() to bytes that are gone. Thanks to Xuanqiang Luo for insisting on this. Also invalidate the inner header state, as suggested by the netdev AI review : https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260911114922.621937-1-edumazet%40google.com

Severity

No CVSS data available.

Assigner

Linux CNA under the mitre root

CNA scorecard D 53/100 over 6664 records in the last 180 days details

References

4 references

URL	Tags
https://git.kernel.org/stable/c/75e4a3e62531738c1…
https://git.kernel.org/stable/c/bff8a8e53a6d290bc…
https://git.kernel.org/stable/c/12929ed66a5166177…
https://git.kernel.org/stable/c/a5117e1eccac6ee3b…

Impacted products

2 products

Vendor	Product	Version
Linux	Linux	Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 75e4a3e62531738c124c8555a626426fca29d392 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < bff8a8e53a6d290bc2777bde36d3cb6317b8463d (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < 12929ed66a5166177ef5f06d3da81e4f99993e90 (git) Affected: 6fa01ccd883021105e9f8af7d04b9f156fa3494a , < a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309 (git)
Linux	Linux	Affected: 4.7 Unaffected: 0 , < 4.7 (semver) Unaffected: 6.12.112 , ≤ 6.12.* (semver) Unaffected: 6.18.54 , ≤ 6.18.* (semver) Unaffected: 7.2.8 , ≤ 7.2.* (semver) Unaffected: 7.3-rc4 , ≤ * (original_commit_for_fix)

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JSON

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  "containers": {
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      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/core/skbuff.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
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              "lessThan": "75e4a3e62531738c124c8555a626426fca29d392",
              "status": "affected",
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              "versionType": "git"
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            {
              "lessThan": "bff8a8e53a6d290bc2777bde36d3cb6317b8463d",
              "status": "affected",
              "version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
              "versionType": "git"
            },
            {
              "lessThan": "12929ed66a5166177ef5f06d3da81e4f99993e90",
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              "versionType": "git"
            },
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              "versionType": "git"
            }
          ]
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        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
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          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.7"
            },
            {
              "lessThan": "4.7",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
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              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.54",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3-rc4",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.112",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.18.54",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2.8",
                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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                  "versionStartIncluding": "4.7",
                  "vulnerable": true
                }
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              "negate": false,
              "operator": "OR"
            }
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: do not leave stale header offsets after pskb_carve()\n\npskb_carve_inside_header() and pskb_carve_inside_nonlinear() remove\nthe first bytes of a packet and reallocate skb-\u003ehead.\n\nAll the headers that were present before the operation are gone,\nbut both functions call skb_headers_offset_update(skb, 0), which\nis a no-op : skb-\u003emac_header, skb-\u003enetwork_header,\nskb-\u003etransport_header and skb-\u003ecsum_start keep their old values and\nnow describe bytes which are no longer there.\n\nBoth helpers size the new head from the old skb_end_offset(), so the\nstale offsets still land inside the new allocation. They point past\nskb_tail_pointer() though, to bytes that were never initialized.\n\npskb_carve_inside_nonlinear() is the worst case, because it leaves a\nzombie skb with an empty linear part (skb-\u003edata ==\nskb_tail_pointer(skb), skb_headlen(skb) == 0), while\nskb_mac_header_was_set() is still true and skb-\u003emac_header is way\nahead of skb-\u003edata.\n\nThe only user of pskb_extract() is rds_tcp_data_recv(), and the\ncarved skb is queued on tinc-\u003eti_skb_list. When the RDS incoming\nmessage is released, rds_tcp_inc_free() calls skb_queue_purge(),\nwhich frees the skbs with SKB_DROP_REASON_QUEUE_PURGE. This is\nvisible from drop_monitor, which then tries to pull back to the\n(bogus) mac header :\n\nskbuff: __skb_pull(len=234)\nskb len=6968 data_len=6968 headroom=0 headlen=0 tailroom=0\nend-tail=384 mac=(234,14) mac_len=14 net=(248,40) trans=288\nshinfo(txflags=0 nr_frags=1 gso(size=1428 type=16 segs=5))\ncsum(0x100120 start=288 offset=16 ip_summed=3 complete_sw=0 valid=1 level=0)\nhash(0x7b446c6c sw=0 l4=1) proto=0x86dd pkttype=0 iif=60\nkernel BUG at ./include/linux/skbuff.h:2847!\n\nAdd skb_carve_reset_headers() to mark the mac and transport headers\nas not set, reset the network header, clear skb-\u003emac_len, and drop\na now meaningless CHECKSUM_PARTIAL (csum_start no longer describes\nanything).\n\nInvalidate the inner offsets as well. Unlike mac_header and\ntransport_header they have no \"unset\" sentinel, so a leftover\nnon-zero value still looks like a real header. Zero\nskb-\u003einner_mac_header, skb-\u003einner_network_header,\nskb-\u003einner_transport_header, skb-\u003einner_protocol and\nskb-\u003eencapsulation, so that all the header state is invalidated in\none place.\n\nv2: fixed an inaccurate changelog. The stale offsets stay inside the\n    new skb-\u003ehead, which is never smaller than the old one, they\n    simply point past skb_tail_pointer() to bytes that are gone.\n    Thanks to Xuanqiang Luo for insisting on this.\n    Also invalidate the inner header state, as suggested by the\n    netdev AI review :\n    https://netdev-ai.bots.linux.dev/sashiko/#/patchset/20260911114922.621937-1-edumazet%40google.com"
        }
      ],
      "providerMetadata": {
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        "shortName": "Linux"
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        {
          "url": "https://git.kernel.org/stable/c/a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309"
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      "title": "net: skbuff: do not leave stale header offsets after pskb_carve()",
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    "cveId": "CVE-2026-98271",
    "datePublished": "2026-10-06T08:45:33.298Z",
    "dateReserved": "2026-09-25T10:25:14.333Z",
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    "state": "PUBLISHED"
  },
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}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

Vulnerability timeline

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The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
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