{"id":"CVE-2023-53600","state":"PUBLISHED","title":"tunnels: fix kasan splat when generating ipv4 pmtu error","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: fix kasan splat when generating ipv4 pmtu error\n\nIf we try to emit an icmp error in response to a nonliner skb, we get\n\nBUG: KASAN: slab-out-of-bounds in ip_compute_csum+0x134/0x220\nRead of size 4 at addr ffff88811c50db00 by task iperf3/1691\nCPU: 2 PID: 1691 Comm: iperf3 Not tainted 6.5.0-rc3+ #309\n[..]\n kasan_report+0x105/0x140\n ip_compute_csum+0x134/0x220\n iptunnel_pmtud_build_icmp+0x554/0x1020\n skb_tunnel_check_pmtu+0x513/0xb80\n vxlan_xmit_one+0x139e/0x2ef0\n vxlan_xmit+0x1867/0x2760\n dev_hard_start_xmit+0x1ee/0x4f0\n br_dev_queue_push_xmit+0x4d1/0x660\n [..]\n\nip_compute_csum() cannot deal with nonlinear skbs, so avoid it.\nAfter this change, splat is gone and iperf3 is no longer stuck.","publishedAt":"2025-10-04T15:44:11.775Z","updatedAt":"2026-10-15T21:41:31.545Z","severity":{"score":9.1,"label":"Critical","version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","source":"Linux"},"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"5850c391fd7e25662334cb3cbf29a62bcbff1084","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"e95808121953410db8c59f0abfde70ac0d34222c","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"fe6a9f7516735be9fdabab00e47ef7a3403a174d","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"6a7ac3d20593865209dceb554d8b3f094c6bd940","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/ip_tunnel_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.9","versionType":"semver"},{"version":"5.10.191","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.127","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.46","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.4.11","status":"unaffected","lessThanOrEqual":"6.4.*","versionType":"semver"},{"version":"6.5","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/ip_tunnel_core.c"]}],"references":["https://git.kernel.org/stable/c/5850c391fd7e25662334cb3cbf29a62bcbff1084","https://git.kernel.org/stable/c/e95808121953410db8c59f0abfde70ac0d34222c","https://git.kernel.org/stable/c/da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc","https://git.kernel.org/stable/c/fe6a9f7516735be9fdabab00e47ef7a3403a174d","https://git.kernel.org/stable/c/6a7ac3d20593865209dceb554d8b3f094c6bd940"],"weaknesses":[],"ingestedAt":"2026-10-29T20:06:33.064Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2023/53xxx/CVE-2023-53600.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2023-53600","state":"PUBLISHED","datePublished":"2025-10-04T15:44:11.775Z","dateUpdated":"2026-10-15T21:41:31.545Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2025-10-04T15:40:38.479Z"},"containers":{"cna":{"title":"tunnels: fix kasan splat when generating ipv4 pmtu error","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ntunnels: fix kasan splat when generating ipv4 pmtu error\n\nIf we try to emit an icmp error in response to a nonliner skb, we get\n\nBUG: KASAN: slab-out-of-bounds in ip_compute_csum+0x134/0x220\nRead of size 4 at addr ffff88811c50db00 by task iperf3/1691\nCPU: 2 PID: 1691 Comm: iperf3 Not tainted 6.5.0-rc3+ #309\n[..]\n kasan_report+0x105/0x140\n ip_compute_csum+0x134/0x220\n iptunnel_pmtud_build_icmp+0x554/0x1020\n skb_tunnel_check_pmtu+0x513/0xb80\n vxlan_xmit_one+0x139e/0x2ef0\n vxlan_xmit+0x1867/0x2760\n dev_hard_start_xmit+0x1ee/0x4f0\n br_dev_queue_push_xmit+0x4d1/0x660\n [..]\n\nip_compute_csum() cannot deal with nonlinear skbs, so avoid it.\nAfter this change, splat is gone and iperf3 is no longer stuck."}],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"5850c391fd7e25662334cb3cbf29a62bcbff1084","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"e95808121953410db8c59f0abfde70ac0d34222c","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"fe6a9f7516735be9fdabab00e47ef7a3403a174d","versionType":"git"},{"version":"4cb47a8644cc9eb8ec81190a50e79e6530d0297f","status":"affected","lessThan":"6a7ac3d20593865209dceb554d8b3f094c6bd940","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/ip_tunnel_core.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"5.9","status":"affected"},{"version":"0","status":"unaffected","lessThan":"5.9","versionType":"semver"},{"version":"5.10.191","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.15.127","status":"unaffected","lessThanOrEqual":"5.15.*","versionType":"semver"},{"version":"6.1.46","status":"unaffected","lessThanOrEqual":"6.1.*","versionType":"semver"},{"version":"6.4.11","status":"unaffected","lessThanOrEqual":"6.4.*","versionType":"semver"},{"version":"6.5","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["net/ipv4/ip_tunnel_core.c"]}],"references":[{"url":"https://git.kernel.org/stable/c/5850c391fd7e25662334cb3cbf29a62bcbff1084"},{"url":"https://git.kernel.org/stable/c/e95808121953410db8c59f0abfde70ac0d34222c"},{"url":"https://git.kernel.org/stable/c/da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc"},{"url":"https://git.kernel.org/stable/c/fe6a9f7516735be9fdabab00e47ef7a3403a174d"},{"url":"https://git.kernel.org/stable/c/6a7ac3d20593865209dceb554d8b3f094c6bd940"}],"metrics":[{"cvssV3_1":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:H","baseScore":9.1,"baseSeverity":"CRITICAL"},"scenarios":[{"lang":"en","value":"AV:N - The vulnerable code runs on the bridge/tunnel forwarding path (`br_dev_queue_push_xmit` → `vxlan_xmit` → `skb_tunnel_check_pmtu`), driven entirely by the size, DF flag and layout of an IP packet that a remote host injected into the bridged VXLAN/Geneve overlay; no local access is needed and the leaked checksum is mailed back to the sender.\nAC:L - The attacker controls every trigger condition — packet size above the tunnel PMTU, the DF bit, and the addresses/protocol that pass the filters in `iptunnel_pmtud_check_icmp()` — and nonlinearity is the default state for large skbs (NIC page frags, GRO, GSO), so the OOB read fires reliably on the first oversized packet.\nPR:N - No privileges exist on this path: the packet is processed unauthenticated on the bridge forwarding/transmit path with no capability, credential or namespace check between packet reception and `ip_compute_csum()`.\nUI:N - No victim action is required; the kernel autonomously generates the PMTU ICMP error as soon as an oversized DF packet is forwarded to the tunnel port.\nS:U - The out-of-bounds read and its effects stay within the kernel's own security authority; no VM, IOMMU or sandbox boundary is crossed.\nC:H - Up to ~514 bytes of slab memory adjacent to the skb head are read out of bounds and folded into the ICMP checksum of a packet sent back to the attacker, disclosing adjacent kernel heap state to an off-host observer.\nI:N - The defect is a pure read overrun — `ip_compute_csum()` only reads, and all writes (`skb_push`, header construction) remain within the region guaranteed by `skb_cow()`, so no kernel memory is modified.\nA:H - The bogus checksum makes the peer drop the ICMP FRAG_NEEDED, black-holing PMTU discovery and hanging tunneled TCP transfers indefinitely (the reported stuck iperf3), and the multi-hundred-byte slab overread oopses the kernel under hardened/debug memory configurations."}]}],"providerMetadata":{"shortName":"Linux","orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateUpdated":"2026-08-05T09:15:04.025Z"},"cpeApplicability":[{"nodes":[{"operator":"OR","negate":false,"cpeMatch":[{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"5.10.191"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"5.15.127"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.1.46"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.4.11"},{"vulnerable":true,"criteria":"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*","versionStartIncluding":"5.9","versionEndExcluding":"6.5"}]}]}],"x_generator":{"engine":"bippy-1.2.0"}},"adp":[{"title":"CISA ADP 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