CVE-2025-71098

ip6_gre: make ip6gre_header() robust

State: Published
Severity: Not scored
Published: Jan 13, 2026
Updated: Oct 19, 2026
Reserved: Jan 13, 2026

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

Scores

The record has no CVSS score.

Weaknesses

CWE-119 Improper Restriction of Operations within the Bounds of a Memory Buffer

Affected Products

Product	Versions
LinuxLinux	c12b395a46646bab69089ce7016ac78177f6001f to before 17e7386234f740f3e7d5e58a47b5847ea34c3bc2Affected c12b395a46646bab69089ce7016ac78177f6001f to before 41a1a3140aff295dee8063906f70a514548105e8Affected c12b395a46646bab69089ce7016ac78177f6001f to before adee129db814474f2f81207bd182bf343832a52eAffected c12b395a46646bab69089ce7016ac78177f6001f to before 1717357007db150c2d703f13f5695460e960f26cAffected c12b395a46646bab69089ce7016ac78177f6001f to before 5fe210533e3459197eabfdbf97327dacbdc04d60Affected c12b395a46646bab69089ce7016ac78177f6001f to before 91a2b25be07ce1a7549ceebbe82017551d2eec92Affected c12b395a46646bab69089ce7016ac78177f6001f to before db5b4e39c4e63700c68a7e65fc4e1f1375273476Affected
LinuxLinux	3.7Affected before 3.7Not affected 5.10.248 through 5.10.Not affected 5.15.198 through 5.15.Not affected 6.1.160 through 6.1.Not affected 6.6.120 through 6.6.Not affected 6.12.64 through 6.12.Not affected 6.18.4 through 6.18.Not affected 6.19 and laterNot affected

Product

Versions

LinuxLinux

c12b395a46646bab69089ce7016ac78177f6001f to before 17e7386234f740f3e7d5e58a47b5847ea34c3bc2Affected
c12b395a46646bab69089ce7016ac78177f6001f to before 41a1a3140aff295dee8063906f70a514548105e8Affected
c12b395a46646bab69089ce7016ac78177f6001f to before adee129db814474f2f81207bd182bf343832a52eAffected
c12b395a46646bab69089ce7016ac78177f6001f to before 1717357007db150c2d703f13f5695460e960f26cAffected
c12b395a46646bab69089ce7016ac78177f6001f to before 5fe210533e3459197eabfdbf97327dacbdc04d60Affected
c12b395a46646bab69089ce7016ac78177f6001f to before 91a2b25be07ce1a7549ceebbe82017551d2eec92Affected
c12b395a46646bab69089ce7016ac78177f6001f to before db5b4e39c4e63700c68a7e65fc4e1f1375273476Affected

LinuxLinux

3.7Affected
before 3.7Not affected
5.10.248 through 5.10.*Not affected
5.15.198 through 5.15.*Not affected
6.1.160 through 6.1.*Not affected
6.6.120 through 6.6.*Not affected
6.12.64 through 6.12.*Not affected
6.18.4 through 6.18.*Not affected
6.19 and laterNot affected

References

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