{"dataType":"CVE_RECORD","cveMetadata":{"cveId":"CVE-2024-26641","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","state":"PUBLISHED","assignerShortName":"Linux","dateReserved":"2024-02-19T14:20:24.137Z","datePublished":"2024-03-18T10:19:07.581Z","dateUpdated":"2026-08-05T11:26:29.008Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2026-08-05T11:26:29.008Z"},"descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()\n\nsyzbot found __ip6_tnl_rcv() could access unitiliazed data [1].\n\nCall pskb_inet_may_pull() to fix this, and initialize ipv6h\nvariable after this call as it can change skb->head.\n\n[1]\n BUG: KMSAN: uninit-value in __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\n BUG: KMSAN: uninit-value in INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n BUG: KMSAN: uninit-value in IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321\n  __INET_ECN_decapsulate include/net/inet_ecn.h:253 [inline]\n  INET_ECN_decapsulate include/net/inet_ecn.h:275 [inline]\n  IP6_ECN_decapsulate+0x7df/0x1e50 include/net/inet_ecn.h:321\n  ip6ip6_dscp_ecn_decapsulate+0x178/0x1b0 net/ipv6/ip6_tunnel.c:727\n  __ip6_tnl_rcv+0xd4e/0x1590 net/ipv6/ip6_tunnel.c:845\n  ip6_tnl_rcv+0xce/0x100 net/ipv6/ip6_tunnel.c:888\n gre_rcv+0x143f/0x1870\n  ip6_protocol_deliver_rcu+0xda6/0x2a60 net/ipv6/ip6_input.c:438\n  ip6_input_finish net/ipv6/ip6_input.c:483 [inline]\n  NF_HOOK include/linux/netfilter.h:314 [inline]\n  ip6_input+0x15d/0x430 net/ipv6/ip6_input.c:492\n  ip6_mc_input+0xa7e/0xc80 net/ipv6/ip6_input.c:586\n  dst_input include/net/dst.h:461 [inline]\n  ip6_rcv_finish+0x5db/0x870 net/ipv6/ip6_input.c:79\n  NF_HOOK include/linux/netfilter.h:314 [inline]\n  ipv6_rcv+0xda/0x390 net/ipv6/ip6_input.c:310\n  __netif_receive_skb_one_core net/core/dev.c:5532 [inline]\n  __netif_receive_skb+0x1a6/0x5a0 net/core/dev.c:5646\n  netif_receive_skb_internal net/core/dev.c:5732 [inline]\n  netif_receive_skb+0x58/0x660 net/core/dev.c:5791\n  tun_rx_batched+0x3ee/0x980 drivers/net/tun.c:1555\n  tun_get_user+0x53af/0x66d0 drivers/net/tun.c:2002\n  tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048\n  call_write_iter include/linux/fs.h:2084 [inline]\n  new_sync_write fs/read_write.c:497 [inline]\n  vfs_write+0x786/0x1200 fs/read_write.c:590\n  ksys_write+0x20f/0x4c0 fs/read_write.c:643\n  __do_sys_write fs/read_write.c:655 [inline]\n  __se_sys_write fs/read_write.c:652 [inline]\n  __x64_sys_write+0x93/0xd0 fs/read_write.c:652\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nUninit was created at:\n  slab_post_alloc_hook+0x129/0xa70 mm/slab.h:768\n  slab_alloc_node mm/slub.c:3478 [inline]\n  kmem_cache_alloc_node+0x5e9/0xb10 mm/slub.c:3523\n  kmalloc_reserve+0x13d/0x4a0 net/core/skbuff.c:560\n  __alloc_skb+0x318/0x740 net/core/skbuff.c:651\n  alloc_skb include/linux/skbuff.h:1286 [inline]\n  alloc_skb_with_frags+0xc8/0xbd0 net/core/skbuff.c:6334\n  sock_alloc_send_pskb+0xa80/0xbf0 net/core/sock.c:2787\n  tun_alloc_skb drivers/net/tun.c:1531 [inline]\n  tun_get_user+0x1e8a/0x66d0 drivers/net/tun.c:1846\n  tun_chr_write_iter+0x3af/0x5d0 drivers/net/tun.c:2048\n  call_write_iter include/linux/fs.h:2084 [inline]\n  new_sync_write fs/read_write.c:497 [inline]\n  vfs_write+0x786/0x1200 fs/read_write.c:590\n  ksys_write+0x20f/0x4c0 fs/read_write.c:643\n  __do_sys_write fs/read_write.c:655 [inline]\n  __se_sys_write fs/read_write.c:652 [inline]\n  __x64_sys_write+0x93/0xd0 fs/read_write.c:652\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0x6d/0x140 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x63/0x6b\n\nCPU: 0 PID: 5034 Comm: syz-executor331 Not tainted 6.7.0-syzkaller-00562-g9f8413c4a66f #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H","baseScore":8.6,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code is in the IPv6 tunnel receive path, reached directly from `ipv6_rcv()` → `ip6_protocol_deliver_rcu()` → `gre_rcv()`/`ip6ip6_rcv()`/`ip4ip6_rcv()` when a host has an ip6tnl, ip6gre, ERSPAN or collect_md tunnel endpoint configured. A remote attacker triggers it purely by sending a crafted IPv6 packet (proto 47/41/4/137) with a truncated inner header.\nAC:L - The attacker fully controls the packet: simply emitting an outer IPv6+GRE header with zero/short inner payload deterministically reaches `dscp_ecn_decapsulate()` with the inner header absent from the linear area. No race, no memory-layout grooming, and no condition outside the attacker's control is required.\nPR:N - Tunnel decapsulation is completely unauthenticated — `ip6_tnl_rcv_ctl()`/`ip6_tnl_lookup()` only compare addresses and keys, and wildcard, `collect_md` and fallback tunnels match arbitrary sources. The attacker needs no account or credentials on the target.\nUI:N - Processing happens automatically in softirq context when the packet is received; no local user has to open, mount, or click anything.\nS:U - The uninitialized read and the out-of-bounds DSCP write are confined to kernel memory managed by the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:L - KMSAN confirms uninitialized kernel heap memory is read and consumed by `__INET_ECN_decapsulate()`, and the outcome is remotely observable (packet dropped vs. delivered, plus the ratelimited \"non-ECT from %pI6 with DS=%#x\" log), giving a repeatable oracle over stale heap contents. The exposure is strictly bounded to a couple of bytes within the skb's own buffer rather than an arbitrary read.\nI:L - On tunnels configured with `IP6_TNL_F_RCV_DSCP_COPY`, `ipv6_change_dsfield()`/`ipv4_change_dsfield()` perform an unchecked read-modify-write beyond the packet data (unlike the bounds-checked `INET_ECN_set_ce()`), modifying kernel memory that does not belong to the packet — in the zero-tailroom case the first bytes of `struct skb_shared_info`. The corruption is a few bytes at a fixed offset, not an arbitrary write.\nA:H - The unchecked DSCP write can land on `skb_shared_info`'s `meta_len` and `frag_list` pointer bytes, corrupting a kernel pointer that is later dereferenced during skb traversal/free, yielding an oops; garbage-driven ECN decisions additionally cause spurious `rx_frame_errors` drops of tunnel traffic, and the condition is a hard KMSAN/instrumented-kernel abort. Any unauthenticated remote peer can repeat it indefinitely."}]}],"affected":[{"product":"Linux","vendor":"Linux","defaultStatus":"unaffected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_tunnel.c"],"versions":[{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"a9bc32879a08f23cdb80a48c738017e39aea1080","status":"affected","versionType":"git"},{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"af6b5c50d47ab43e5272ad61935d0ed2e264d3f0","status":"affected","versionType":"git"},{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"d54e4da98bbfa8c257bdca94c49652d81d18a4d8","status":"affected","versionType":"git"},{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"350a6640fac4b53564ec20aa3f4a0922cb0ba5e6","status":"affected","versionType":"git"},{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"c835df3bcc14858ae9b27315dd7de76370b94f3a","status":"affected","versionType":"git"},{"version":"0d3c703a9d1723c7707e0680019ac8ff5922db42","lessThan":"8d975c15c0cd744000ca386247432d57b21f9df0","status":"affected","versionType":"git"}]},{"product":"Linux","vendor":"Linux","defaultStatus":"affected","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv6/ip6_tunnel.c"],"versions":[{"version":"4.7","status":"affected"},{"version":"0","lessThan":"4.7","status":"unaffected","versionType":"semver"},{"version":"5.10.210","lessThanOrEqual":"5.10.*","status":"unaffected","versionType":"semver"},{"version":"5.15.149","lessThanOrEqual":"5.15.*","status":"unaffected","versionType":"semver"},{"version":"6.1.77","lessThanOrEqual":"6.1.*","status":"unaffected","versionType":"semver"},{"version":"6.6.16","lessThanOrEqual":"6.6.*","status":"unaffected","versionType":"semver"},{"version":"6.7.4","lessThanOrEqual":"6.7.*","status":"unaffected","versionType":"semver"},{"version":"6.8","lessThanOrEqual":"*","status":"unaffected","versionType":"original_commit_for_fix"}]}],"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.10.210"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"5.15.149"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.1.77"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.6.16"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.7.4"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"4.7","versionEndExcluding":"6.8"}]}]}],"references":[{"url":"https://git.kernel.org/stable/c/a9bc32879a08f23cdb80a48c738017e39aea1080"},{"url":"https://git.kernel.org/stable/c/af6b5c50d47ab43e5272ad61935d0ed2e264d3f0"},{"url":"https://git.kernel.org/stable/c/d54e4da98bbfa8c257bdca94c49652d81d18a4d8"},{"url":"https://git.kernel.org/stable/c/350a6640fac4b53564ec20aa3f4a0922cb0ba5e6"},{"url":"https://git.kernel.org/stable/c/c835df3bcc14858ae9b27315dd7de76370b94f3a"},{"url":"https://git.kernel.org/stable/c/8d975c15c0cd744000ca386247432d57b21f9df0"}],"title":"ip6_tunnel: make sure to pull inner header in __ip6_tnl_rcv()","x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2024-06-21T16:08:53.324454Z","id":"CVE-2024-26641","options":[{"Exploitation":"none"},{"Automatable":"no"},{"Technical Impact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"title":"CISA ADP Vulnrichment","providerMetadata":{"orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","shortName":"CISA-ADP","dateUpdated":"2024-06-21T16:09:02.235Z"}},{"title":"CVE Program Container","references":[{"url":"https://git.kernel.org/stable/c/a9bc32879a08f23cdb80a48c738017e39aea1080","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/af6b5c50d47ab43e5272ad61935d0ed2e264d3f0","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/d54e4da98bbfa8c257bdca94c49652d81d18a4d8","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/350a6640fac4b53564ec20aa3f4a0922cb0ba5e6","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/c835df3bcc14858ae9b27315dd7de76370b94f3a","tags":["x_transferred"]},{"url":"https://git.kernel.org/stable/c/8d975c15c0cd744000ca386247432d57b21f9df0","tags":["x_transferred"]},{"url":"https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html","tags":["x_transferred"]},{"url":"https://security.netapp.com/advisory/ntap-20241108-0008/"}],"providerMetadata":{"orgId":"af854a3a-2127-422b-91ae-364da2661108","shortName":"CVE","dateUpdated":"2024-11-08T15:02:48.742Z"}}]},"dataVersion":"5.2"}