CVE-2026-98271
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.
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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.
Detalles técnicos trazas, registros y código del informe original
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.comCVSS
NVD no ha asignado puntuación CVSS a esta CVE (habitual desde el cambio de política de abril de 2026).
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.18%
- Percentil entre todas las CVEs puntuadas: 6
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
Tecnologías afectadas (1)
⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.
Referencias
JSON original (NVD)
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{
"id": "CVE-2026-98271",
"cveTags": [],
"metrics": {},
"affected": [
{
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
"affectedData": [
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"lessThan": "75e4a3e62531738c124c8555a626426fca29d392",
"versionType": "git"
},
{
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"lessThan": "bff8a8e53a6d290bc2777bde36d3cb6317b8463d",
"versionType": "git"
},
{
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"lessThan": "12929ed66a5166177ef5f06d3da81e4f99993e90",
"versionType": "git"
},
{
"status": "affected",
"version": "6fa01ccd883021105e9f8af7d04b9f156fa3494a",
"lessThan": "a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309",
"versionType": "git"
}
],
"programFiles": [
"net/core/skbuff.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.7"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.7",
"versionType": "semver"
},
{
"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-rc4",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/core/skbuff.c"
],
"defaultStatus": "affected"
}
]
}
],
"published": "2026-10-06T09:18:16.627",
"references": [
{
"url": "https://git.kernel.org/stable/c/12929ed66a5166177ef5f06d3da81e4f99993e90",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/75e4a3e62531738c124c8555a626426fca29d392",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/a5117e1eccac6ee3bd4aed7cacf8ebcb6b3eb309",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
},
{
"url": "https://git.kernel.org/stable/c/bff8a8e53a6d290bc2777bde36d3cb6317b8463d",
"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}
],
"vulnStatus": "Received",
"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->head.\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->mac_header, skb->network_header,\nskb->transport_header and skb->csum_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->data ==\nskb_tail_pointer(skb), skb_headlen(skb) == 0), while\nskb_mac_header_was_set() is still true and skb->mac_header is way\nahead of skb->data.\n\nThe only user of pskb_extract() is rds_tcp_data_recv(), and the\ncarved skb is queued on tinc->ti_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->mac_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->inner_mac_header, skb->inner_network_header,\nskb->inner_transport_header, skb->inner_protocol and\nskb->encapsulation, 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->head, 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"
}
],
"lastModified": "2026-10-06T09:18:16.627",
"sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}