ipv6: ensure sane device mtu in tunnels

Description

In the Linux kernel, the following vulnerability has been resolved: ipv6: ensure sane device mtu in tunnels Another syzbot report [1] with no reproducer hints at a bug in ip6_gre tunnel (dev:ip6gretap0) Since ipv6 mcast code makes sure to read dev->mtu once and applies a sanity check on it (see commit b9b312a7a451 "ipv6: mcast: better catch silly mtu values"), a remaining possibility is that a layer is able to set dev->mtu to an underflowed value (high order bit set). This could happen indeed in ip6gre_tnl_link_config_route(), ip6_tnl_link_config() and ipip6_tunnel_bind_dev() Make sure to sanitize mtu value in a local variable before it is written once on dev->mtu, as lockless readers could catch wrong temporary value. [1] skbuff: skb_over_panic: text:ffff80000b7a2f38 len:40 put:40 head:ffff000149dcf200 data:ffff000149dcf2b0 tail:0xd8 end:0xc0 dev:ip6gretap0 ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:120 Internal error: Oops - BUG: 00000000f2000800 [#1] PREEMPT SMP Modules linked in: CPU: 1 PID: 10241 Comm: kworker/1:1 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022 Workqueue: mld mld_ifc_work pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) pc : skb_panic+0x4c/0x50 net/core/skbuff.c:116 lr : skb_panic+0x4c/0x50 net/core/skbuff.c:116 sp : ffff800020dd3b60 x29: ffff800020dd3b70 x28: 0000000000000000 x27: ffff00010df2a800 x26: 00000000000000c0 x25: 00000000000000b0 x24: ffff000149dcf200 x23: 00000000000000c0 x22: 00000000000000d8 x21: ffff80000b7a2f38 x20: ffff00014c2f7800 x19: 0000000000000028 x18: 00000000000001a9 x17: 0000000000000000 x16: ffff80000db49158 x15: ffff000113bf1a80 x14: 0000000000000000 x13: 00000000ffffffff x12: ffff000113bf1a80 x11: ff808000081c0d5c x10: 0000000000000000 x9 : 73f125dc5c63ba00 x8 : 73f125dc5c63ba00 x7 : ffff800008161d1c x6 : 0000000000000000 x5 : 0000000000000080 x4 : 0000000000000001 x3 : 0000000000000000 x2 : ffff0001fefddcd0 x1 : 0000000100000000 x0 : 0000000000000089 Call trace: skb_panic+0x4c/0x50 net/core/skbuff.c:116 skb_over_panic net/core/skbuff.c:125 [inline] skb_put+0xd4/0xdc net/core/skbuff.c:2049 ip6_mc_hdr net/ipv6/mcast.c:1714 [inline] mld_newpack+0x14c/0x270 net/ipv6/mcast.c:1765 add_grhead net/ipv6/mcast.c:1851 [inline] add_grec+0xa20/0xae0 net/ipv6/mcast.c:1989 mld_send_cr+0x438/0x5a8 net/ipv6/mcast.c:2115 mld_ifc_work+0x38/0x290 net/ipv6/mcast.c:2653 process_one_work+0x2d8/0x504 kernel/workqueue.c:2289 worker_thread+0x340/0x610 kernel/workqueue.c:2436 kthread+0x12c/0x158 kernel/kthread.c:376 ret_from_fork+0x10/0x20 arch/arm64/kernel/entry.S:860 Code: 91011400 aa0803e1 a90027ea 94373093 (d4210000)

Scores

No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Deferred.

EPSS (exploitation in 30 days)

0.25% · top 83% of all CVEs (6 Nov 2026)

The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.

Affected products

• Linux · Linux

  • affected c12b395a46646bab69089ce7016ac78177f6001f – < 2bab6fa449d16af36d9c9518865f783a15f446c7
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < 78297d513157a31fd629626fe4cbb85a7dcbb94a
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < af51fc23a03f02b0c6df09ab0d60f23794436052
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < 44affe7ede596f078c4f2f41e0d160266ccda818
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < ad3f1d9bf162c487d23df684852597961b745cae
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < ccd94bd4939690e24d13e23814bce7ed853a09f3
  • affected c12b395a46646bab69089ce7016ac78177f6001f – < d89d7ff01235f218dad37de84457717f699dee79

• Linux · Linux

  • affected 3.7
  • unaffected < 3.7
  • unaffected 4.14.305 – ≤ 4.14.*
  • unaffected 4.19.272 – ≤ 4.19.*
  • unaffected 5.4.231 – ≤ 5.4.*
  • unaffected 5.10.153 – ≤ 5.10.*
  • unaffected 5.15.77 – ≤ 5.15.*
  • unaffected 6.0.7 – ≤ 6.0.*
  • unaffected 6.1 – ≤ *

References (7)

• https://git.kernel.org/stable/c/2bab6fa449d16af36d9c9518865f783a15f446c7 (opens in a new tab)
• https://git.kernel.org/stable/c/78297d513157a31fd629626fe4cbb85a7dcbb94a (opens in a new tab)
• https://git.kernel.org/stable/c/af51fc23a03f02b0c6df09ab0d60f23794436052 (opens in a new tab)
• https://git.kernel.org/stable/c/44affe7ede596f078c4f2f41e0d160266ccda818 (opens in a new tab)
• https://git.kernel.org/stable/c/ad3f1d9bf162c487d23df684852597961b745cae (opens in a new tab)
• https://git.kernel.org/stable/c/ccd94bd4939690e24d13e23814bce7ed853a09f3 (opens in a new tab)
• https://git.kernel.org/stable/c/d89d7ff01235f218dad37de84457717f699dee79 (opens in a new tab)

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2022-50816](https://trackcve.app/badge/CVE-2022-50816.svg)](https://trackcve.app/cve/CVE-2022-50816)

Record last updated 11 May 2026, 19:25 UTC.