{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2023-53600", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2025-10-04T15:40:38.479Z", "datePublished": "2025-10-04T15:44:11.775Z", "dateUpdated": "2026-08-05T09:15:04.025Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T09:15:04.025Z" }, "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." } ], "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." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/ip_tunnel_core.c" ], "versions": [ { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "5850c391fd7e25662334cb3cbf29a62bcbff1084", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "e95808121953410db8c59f0abfde70ac0d34222c", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "da5f42a6e7485fbb7a6dbd6a2b3045e19e4df5cc", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "fe6a9f7516735be9fdabab00e47ef7a3403a174d", "status": "affected", "versionType": "git" }, { "version": "4cb47a8644cc9eb8ec81190a50e79e6530d0297f", "lessThan": "6a7ac3d20593865209dceb554d8b3f094c6bd940", "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/ipv4/ip_tunnel_core.c" ], "versions": [ { "version": "5.9", "status": "affected" }, { "version": "0", "lessThan": "5.9", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.191", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.127", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.46", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.4.11", "lessThanOrEqual": "6.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.5", "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": "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" } ] } ] } ], "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" } ], "title": "tunnels: fix kasan splat when generating ipv4 pmtu error", "x_generator": { "engine": "bippy-1.2.0" } } } }