{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-64132", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-07-19T07:54:57.036Z", "datePublished": "2026-07-19T15:40:27.590Z", "dateUpdated": "2026-08-05T12:39:34.060Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:39:34.060Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: ioam: refresh hdr pointer before ioam6_event()\n\nReported by Sashiko:\n\nIn ipv6_hop_ioam(), the hdr pointer is initialized to point into the\nskb's linear data buffer. Later, the code calls skb_ensure_writable(),\nwhich might reallocate the buffer:\n\n\tif (skb_ensure_writable(skb, optoff + 2 + hdr->opt_len))\n\t\tgoto drop;\n\n\t/* Trace pointer may have changed */\n\ttrace = (struct ioam6_trace_hdr *)(skb_network_header(skb)\n\t\t\t\t\t + optoff + sizeof(*hdr));\n\n\tioam6_fill_trace_data(skb, ns, trace, true);\n\n\tioam6_event(IOAM6_EVENT_TRACE, dev_net(skb->dev),\n\t\t GFP_ATOMIC, (void *)trace, hdr->opt_len - 2);\n\nIf the skb is cloned or lacks sufficient linear headroom,\nskb_ensure_writable() will invoke pskb_expand_head(), which reallocates\nthe skb's data buffer and frees the old one, invalidating pointers to\nit. While the code recalculates the trace pointer immediately after the\ncall to skb_ensure_writable(), it fails to recalculate the hdr pointer.\n\nThis patch fixes the above by recalculating the hdr pointer before\npassing hdr->opt_len to ioam6_event(), so that we avoid any UaF." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - The bug is in `ipv6_hop_ioam()`, reached from `ipv6_rcv()` → `ip6_rcv_core()` → `ipv6_parse_hopopts()` → `ip6_parse_tlv()` when processing IPv6 hop-by-hop IOAM options on ingress. A remote attacker can deliver the trigger with a crafted IPv6 packet to any internet-facing or LAN-reachable host/router that has IOAM ingress enabled.\nAC:L - Exploitation requires `skb_ensure_writable()` to reallocate via `pskb_expand_head()`, which occurs when the skb is cloned (e.g., bridge flooding/multicast forwarding sets `skb->cloned` on the original before local delivery to the IP stack). An attacker can reliably create this condition with concurrent traffic/topology choices rather than depending on uncontrollable timing or memory layout.\nPR:N - The attacker needs no privileges on the victim system—only the ability to send IPv6 packets. IOAM namespace/sysctl configuration is a victim-side deployment prerequisite (typical on carrier/ISP telemetry nodes), not a privilege the attacker must hold.\nUI:N - Exploitation is fully attacker-driven by sending a malicious IPv6 packet and requires no action from a victim user.\nS:U - The vulnerability is a kernel heap use-after-free in IPv6 packet processing; successful exploitation would compromise the kernel/host itself, not cross a separate security authority such as a VM guest-to-host or sandbox boundary.\nC:H - After `pskb_expand_head()` frees the old skb buffer, the stale `hdr` pointer is dereferenced for `hdr->opt_len`, constituting a use-after-free read of freed kernel memory; that attacker-influenced length is then used in `ioam6_event_put_trace()`/`nla_put()`, enabling out-of-bounds kernel memory reads and information disclosure.\nI:H - Use-after-free of heap metadata enables memory corruption primitives; the corrupted `opt_len` fed into netlink attribute construction can cause out-of-bounds reads whose contents are attacker-influenced, and UAF bugs in skb handling are classically leveragable toward arbitrary kernel write/code execution.\nA:H - Reading freed memory and passing a corrupted length into `nla_put()` can cause kernel oops/panic (especially with KASAN/overflow checks), and UAF conditions inherently risk system crashes even when full exploitation is not attempted." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv6/exthdrs.c" ], "versions": [ { "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3", "lessThan": "769723124b7c3b2bfea4cf68ad292698b87c8d01", "status": "affected", "versionType": "git" }, { "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3", "lessThan": "24de676da63c1122d2c13b0d546238b66d1b4e62", "status": "affected", "versionType": "git" }, { "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3", "lessThan": "5af905aa8e91ff8d94572a1e089558f21dcf24ed", "status": "affected", "versionType": "git" }, { "version": "f655c78d6225f585ef60a9d93ffb79d507ff3ad3", "lessThan": "e46e6bc97fb1f339730ff1ba74267fbf48e7a422", "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/exthdrs.c" ], "versions": [ { "version": "6.9", "status": "affected" }, { "version": "0", "lessThan": "6.9", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.92", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.34", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.11", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "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": "6.9", "versionEndExcluding": "6.12.92" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "6.18.34" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.0.11" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.9", "versionEndExcluding": "7.1" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/769723124b7c3b2bfea4cf68ad292698b87c8d01" }, { "url": "https://git.kernel.org/stable/c/24de676da63c1122d2c13b0d546238b66d1b4e62" }, { "url": "https://git.kernel.org/stable/c/5af905aa8e91ff8d94572a1e089558f21dcf24ed" }, { "url": "https://git.kernel.org/stable/c/e46e6bc97fb1f339730ff1ba74267fbf48e7a422" } ], "title": "ipv6: ioam: refresh hdr pointer before ioam6_event()", "x_generator": { "engine": "bippy-1.2.0" } } } }