CVE-2025-71098
Status: ModifiedMedium (5.5)—
In the Linux kernel, the following vulnerability has been resolved:
ip6_gre: make ip6gre_header() robust
Over the years, syzbot found many ways to crash the kernel in ip6gre_header() [1].
This involves team or bonding drivers ability to dynamically change their dev->needed_headroom and/or dev->hard_header_len
In this particular crash mld_newpack() allocated an skb with a too small reserve/headroom, and by the time mld_sendpack() was called, syzbot managed to attach an ip6gre device.
Technical details traces, logs and code from the original report
[1] skbuff: skb_under_panic: text:ffffffff8a1d69a8 len:136 put:40 head:ffff888059bc7000 data:ffff888059bc6fe8 tail:0x70 end:0x6c0 dev:team0 ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:213 ! <TASK> skb_under_panic net/core/skbuff.c:223 [inline] skb_push+0xc3/0xe0 net/core/skbuff.c:2641 ip6gre_header+0xc8/0x790 net/ipv6/ip6_gre.c:1371 dev_hard_header include/linux/netdevice.h:3436 [inline] neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618 neigh_output include/net/neighbour.h:556 [inline] ip6_finish_output2+0xfb3/0x1480 net/ipv6/ip6_output.c:136 __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline] ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:220 NF_HOOK_COND include/linux/netfilter.h:307 [inline] ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247 NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318 mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855 mld_send_cr net/ipv6/mcast.c:2154 [inline] mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693
CVSS
- Version: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Base score: 5.5
Exploitation probability (EPSS)
- Probability of exploitation in the next 30 days: 0.13%
- Percentile among all scored CVEs: 2
- Score date: 10/4/2026
EPSS (Exploit Prediction Scoring System, FIRST) estimates how likely a vulnerability is to be exploited in the wild within 30 days. It complements CVSS (impact) and CISA KEV (confirmed exploitation).
Affected technologies (1)
CWEs
- CWE-476
References
- https://git.kernel.org/stable/c/1717357007db150c2d703f13f5695460e960f26c
- https://git.kernel.org/stable/c/17e7386234f740f3e7d5e58a47b5847ea34c3bc2
- https://git.kernel.org/stable/c/41a1a3140aff295dee8063906f70a514548105e8
- https://git.kernel.org/stable/c/5fe210533e3459197eabfdbf97327dacbdc04d60
- https://git.kernel.org/stable/c/91a2b25be07ce1a7549ceebbe82017551d2eec92
- https://git.kernel.org/stable/c/adee129db814474f2f81207bd182bf343832a52e
- https://git.kernel.org/stable/c/db5b4e39c4e63700c68a7e65fc4e1f1375273476
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
Raw JSON (NVD)
Show
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"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nip6_gre: make ip6gre_header() robust\n\nOver the years, syzbot found many ways to crash the kernel\nin ip6gre_header() [1].\n\nThis involves team or bonding drivers ability to dynamically\nchange their dev->needed_headroom and/or dev->hard_header_len\n\nIn this particular crash mld_newpack() allocated an skb\nwith a too small reserve/headroom, and by the time mld_sendpack()\nwas called, syzbot managed to attach an ip6gre device.\n\n[1]\nskbuff: skb_under_panic: text:ffffffff8a1d69a8 len:136 put:40 head:ffff888059bc7000 data:ffff888059bc6fe8 tail:0x70 end:0x6c0 dev:team0\n------------[ cut here ]------------\n kernel BUG at net/core/skbuff.c:213 !\n <TASK>\n skb_under_panic net/core/skbuff.c:223 [inline]\n skb_push+0xc3/0xe0 net/core/skbuff.c:2641\n ip6gre_header+0xc8/0x790 net/ipv6/ip6_gre.c:1371\n dev_hard_header include/linux/netdevice.h:3436 [inline]\n neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618\n neigh_output include/net/neighbour.h:556 [inline]\n ip6_finish_output2+0xfb3/0x1480 net/ipv6/ip6_output.c:136\n __ip6_finish_output net/ipv6/ip6_output.c:-1 [inline]\n ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:220\n NF_HOOK_COND include/linux/netfilter.h:307 [inline]\n ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247\n NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318\n mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855\n mld_send_cr net/ipv6/mcast.c:2154 [inline]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693"
},
{
"lang": "es",
"value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nip6_gre: hacer que ip6gre_header() sea robusto\n\nA lo largo de los años, syzbot encontró muchas maneras de colapsar el kernel en ip6gre_header() [1].\n\nEsto implica la capacidad de los controladores de equipo o de enlace (bonding) de cambiar dinámicamente su dev->needed_headroom y/o dev->hard_header_len\n\nEn este colapso particular, mld_newpack() asignó un skb con una reserva/espacio de cabecera (headroom) demasiado pequeño, y para cuando se llamó a mld_sendpack(), syzbot logró adjuntar un dispositivo ip6gre.\n\n[1]\nskbuff: skb_under_panic: texto:ffffffff8a1d69a8 longitud:136 puesto:40 cabecera:ffff888059bc7000 datos:ffff888059bc6fe8 cola:0x70 fin:0x6c0 dispositivo:team0\n------------[ cortar aquí ]------------\n BUG del kernel en net/core/skbuff.c:213 !\n \n skb_under_panic net/core/skbuff.c:223 [en línea]\n skb_push+0xc3/0xe0 net/core/skbuff.c:2641\n ip6gre_header+0xc8/0x790 net/ipv6/ip6_gre.c:1371\n dev_hard_header include/linux/netdevice.h:3436 [en línea]\n neigh_connected_output+0x286/0x460 net/core/neighbour.c:1618\n neigh_output include/net/neighbour.h:556 [en línea]\n ip6_finish_output2+0xfb3/0x1480 net/ipv6/ip6_output.c:136\n __ip6_finish_output net/ipv6/ip6_output.c:-1 [en línea]\n ip6_finish_output+0x234/0x7d0 net/ipv6/ip6_output.c:220\n NF_HOOK_COND include/linux/netfilter.h:307 [en línea]\n ip6_output+0x340/0x550 net/ipv6/ip6_output.c:247\n NF_HOOK+0x9e/0x380 include/linux/netfilter.h:318\n mld_sendpack+0x8d4/0xe60 net/ipv6/mcast.c:1855\n mld_send_cr net/ipv6/mcast.c:2154 [en línea]\n mld_ifc_work+0x83e/0xd60 net/ipv6/mcast.c:2693"
}
],
"lastModified": "2026-07-14T13:18:02.943",
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