{"id":"CVE-2025-38572","state":"PUBLISHED","title":"ipv6: reject malicious packets in ipv6_gso_segment()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: reject malicious packets in ipv6_gso_segment()\n\nsyzbot was able to craft a packet with very long IPv6 extension headers\nleading to an overflow of skb->transport_header.\n\nThis 16bit field has a limited range.\n\nAdd skb_reset_transport_header_careful() helper and use it\nfrom ipv6_gso_segment()\n\nWARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline]\nWARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151\nModules linked in:\nCPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\n RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline]\n RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151\nCall Trace:\n <TASK>\n  skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53\n  nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110\n  skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53\n  __skb_gso_segment+0x342/0x510 net/core/gso.c:124\n  skb_gso_segment include/net/gso.h:83 [inline]\n  validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950\n  validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000\n  sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329\n  __dev_xmit_skb net/core/dev.c:4102 [inline]\n  __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679","publishedAt":"2025-08-19T17:02:52.340Z","updatedAt":"2026-08-05T12:03:00.703Z","severity":{"score":7.8,"label":"High","version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"5dc60b2a00ed7629214ac0c48e43f40af2078703","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"3f638e0b28bde7c3354a0df938ab3a96739455d1","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"09ff062b89d8e48165247d677d1ca23d6d607e9b","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"de322cdf600fc9433845a9e944d1ca6b31cfb67e","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"ef05007b403dcc21e701cb1f30d4572ac0a9da20","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"5489e7fc6f8be3062f8cb7e49406de4bfd94db67","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"573b8250fc2554761db3bc2bbdbab23789d52d4e","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"ee851768e4b8371ce151fd446d24bf3ae2d18789","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"d45cf1e7d7180256e17c9ce88e32e8061a7887fe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/ipv6/ip6_offload.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.8","versionType":"semver"},{"version":"5.4.297","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.241","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.190","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.148","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.102","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.42","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.10","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16.1","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/ipv6/ip6_offload.c"]}],"references":["https://git.kernel.org/stable/c/5dc60b2a00ed7629214ac0c48e43f40af2078703","https://git.kernel.org/stable/c/3f638e0b28bde7c3354a0df938ab3a96739455d1","https://git.kernel.org/stable/c/09ff062b89d8e48165247d677d1ca23d6d607e9b","https://git.kernel.org/stable/c/de322cdf600fc9433845a9e944d1ca6b31cfb67e","https://git.kernel.org/stable/c/ef05007b403dcc21e701cb1f30d4572ac0a9da20","https://git.kernel.org/stable/c/5489e7fc6f8be3062f8cb7e49406de4bfd94db67","https://git.kernel.org/stable/c/573b8250fc2554761db3bc2bbdbab23789d52d4e","https://git.kernel.org/stable/c/ee851768e4b8371ce151fd446d24bf3ae2d18789","https://git.kernel.org/stable/c/d45cf1e7d7180256e17c9ce88e32e8061a7887fe","https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html","https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"],"weaknesses":[],"ingestedAt":"2026-10-29T20:09:09.358Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/38xxx/CVE-2025-38572.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2025-38572","state":"PUBLISHED","datePublished":"2025-08-19T17:02:52.340Z","dateUpdated":"2026-08-05T12:03:00.703Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-04-16T04:51:24.025Z"},"containers":{"cna":{"title":"ipv6: reject malicious packets in ipv6_gso_segment()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: reject malicious packets in ipv6_gso_segment()\n\nsyzbot was able to craft a packet with very long IPv6 extension headers\nleading to an overflow of skb->transport_header.\n\nThis 16bit field has a limited range.\n\nAdd skb_reset_transport_header_careful() helper and use it\nfrom ipv6_gso_segment()\n\nWARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 skb_reset_transport_header include/linux/skbuff.h:3032 [inline]\nWARNING: CPU: 0 PID: 5871 at ./include/linux/skbuff.h:3032 ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151\nModules linked in:\nCPU: 0 UID: 0 PID: 5871 Comm: syz-executor211 Not tainted 6.16.0-rc6-syzkaller-g7abc678e3084 #0 PREEMPT(full)\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025\n RIP: 0010:skb_reset_transport_header include/linux/skbuff.h:3032 [inline]\n RIP: 0010:ipv6_gso_segment+0x15e2/0x21e0 net/ipv6/ip6_offload.c:151\nCall Trace:\n <TASK>\n  skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53\n  nsh_gso_segment+0x54a/0xe10 net/nsh/nsh.c:110\n  skb_mac_gso_segment+0x31c/0x640 net/core/gso.c:53\n  __skb_gso_segment+0x342/0x510 net/core/gso.c:124\n  skb_gso_segment include/net/gso.h:83 [inline]\n  validate_xmit_skb+0x857/0x11b0 net/core/dev.c:3950\n  validate_xmit_skb_list+0x84/0x120 net/core/dev.c:4000\n  sch_direct_xmit+0xd3/0x4b0 net/sched/sch_generic.c:329\n  __dev_xmit_skb net/core/dev.c:4102 [inline]\n  __dev_queue_xmit+0x17b6/0x3a70 net/core/dev.c:4679"}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"5dc60b2a00ed7629214ac0c48e43f40af2078703","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"3f638e0b28bde7c3354a0df938ab3a96739455d1","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"09ff062b89d8e48165247d677d1ca23d6d607e9b","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"de322cdf600fc9433845a9e944d1ca6b31cfb67e","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"ef05007b403dcc21e701cb1f30d4572ac0a9da20","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"5489e7fc6f8be3062f8cb7e49406de4bfd94db67","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"573b8250fc2554761db3bc2bbdbab23789d52d4e","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"ee851768e4b8371ce151fd446d24bf3ae2d18789","versionType":"git"},{"version":"d1da932ed4ecad2a14cbcc01ed589d617d0f0f09","status":"affected","lessThan":"d45cf1e7d7180256e17c9ce88e32e8061a7887fe","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/ipv6/ip6_offload.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"3.8","status":"affected"},{"version":"0","status":"unaffected","lessThan":"3.8","versionType":"semver"},{"version":"5.4.297","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.241","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.190","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.148","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.6.102","status":"unaffected","lessThanOrEqual":"6.6.*","versionType":"semver"},{"version":"6.12.42","status":"unaffected","lessThanOrEqual":"6.12.*","versionType":"semver"},{"version":"6.15.10","status":"unaffected","lessThanOrEqual":"6.15.*","versionType":"semver"},{"version":"6.16.1","status":"unaffected","lessThanOrEqual":"6.16.*","versionType":"semver"},{"version":"6.17","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["include/linux/skbuff.h","net/ipv6/ip6_offload.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5dc60b2a00ed7629214ac0c48e43f40af2078703"},{"url":"https://git.kernel.org/stable/c/3f638e0b28bde7c3354a0df938ab3a96739455d1"},{"url":"https://git.kernel.org/stable/c/09ff062b89d8e48165247d677d1ca23d6d607e9b"},{"url":"https://git.kernel.org/stable/c/de322cdf600fc9433845a9e944d1ca6b31cfb67e"},{"url":"https://git.kernel.org/stable/c/ef05007b403dcc21e701cb1f30d4572ac0a9da20"},{"url":"https://git.kernel.org/stable/c/5489e7fc6f8be3062f8cb7e49406de4bfd94db67"},{"url":"https://git.kernel.org/stable/c/573b8250fc2554761db3bc2bbdbab23789d52d4e"},{"url":"https://git.kernel.org/stable/c/ee851768e4b8371ce151fd446d24bf3ae2d18789"},{"url":"https://git.kernel.org/stable/c/d45cf1e7d7180256e17c9ce88e32e8061a7887fe"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","baseScore":7.8,"baseSeverity":"HIGH"},"scenarios":[{"lang":"en","value":"AV:L - The overflow is in the transmit-side GSO segmentation path (`validate_xmit_skb` → `__skb_gso_segment` → `ipv6_gso_segment`), reached by locally injecting a crafted GSO skb via an `AF_PACKET`/`PACKET_VNET_HDR` socket or a tun/tap device. A >64KB extension-header chain cannot be delivered in a single frame over any real link and GRO does not grow the header chain, so a purely remote packet cannot reach it.\nAC:L - The attacker fully controls the number and size of IPv6 extension headers, the linear-area size (`vnet_hdr.hdr_len`), the gso_type/gso_size and `csum_start`, so `skb->data - skb->head` can be driven deterministically past 65535 and made to satisfy the `skb_checksum_start() != skb_transport_header()` guard in `tcp_gso_segment()`. No race, timing window, or memory grooming is involved.\nPR:L - A local socket is required, but `unshare -Urn` gives any unprivileged user CAP_NET_RAW and CAP_NET_ADMIN inside a fresh user+net namespace — enough to open an `AF_PACKET` socket, disable GSO offload on a veth/dummy, and transmit; the `IPV6_2292PKTOPTIONS` (64KB) plus `UDP_SEGMENT` route needs no capability at all.\nUI:N - The attacking process triggers the flaw entirely on its own by sending a packet; no victim action such as mounting, opening a file, or connecting is required.\nS:U - The truncated header offset and all resulting bad accesses stay inside the kernel's own security authority — no hypervisor, IOMMU, or sandbox boundary is crossed.\nC:H - `skb_transport_header()` is left pointing at an attacker-chosen wrong location and `skb_network_header_len()` wraps to a ~64K u16, so segmentation reads header fields and copies data from out-of-bounds/unintended offsets into the emitted segments, which are then transmitted on the wire — an unbounded disclosure primitive rather than a few strictly bounded bytes.\nI:H - The corrupted offset is propagated into every segment by `__copy_skb_header()`/`skb_headers_offset_update()` (u16 arithmetic that itself wraps), and the callbacks then write `th->seq`, `th->check`, `th->fin/psh/cwr`, `uh->len`, `uh->check` and `*prevhdr` through it, giving attacker-directed writes at offsets the kernel never validated.\nA:H - The negative `skb_transport_offset()` flows into `skb_push()`/length computations in `skb_segment()`/`skb_segment_list()` where it can trip `skb_under_panic()`, each segment forces a >64KB allocation, and on `CONFIG_DEBUG_NET`/`panic_on_warn` kernels the `WARN` in `skb_reset_transport_header()` panics outright — all repeatable at will from an unprivileged process."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T12:03:00.703Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.4.297"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.10.241"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"5.15.190"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.1.148"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.6.102"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.12.42"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.15.10"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.16.1"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"3.8","versionEndExcluding":"6.17"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CVE Program Container","references":[{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00008.html"},{"url":"https://lists.debian.org/debian-lts-announce/2025/10/msg00007.html"}],"providerMetadata":{"shortName":"CVE","orgId":"af854a3a-2127-422b-91ae-364da2661108","dateUpdated":"2025-11-03T17:39:59.107Z"}}]}}}