{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-72493", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-08-09T03:40:39.937Z", "datePublished": "2026-08-15T05:57:27.642Z", "dateUpdated": "2026-08-17T05:44:54.422Z"}, "containers": {"cna": {"providerMetadata": {"orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-17T05:44:54.422Z"}, "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: serialize netif_running() check in enqueue_to_backlog()\n\nSyzbot reported a KASAN slab-use-after-free in fib_rules_lookup().\n\nThe root cause is a race condition where packets can escape the backlog\nflushing during device unregistration (e.g., during netns exit).\n\nCommit e9e4dd3267d0 (\"net: do not process device backlog during unregistration\")\nintroduced a lockless netif_running() check in enqueue_to_backlog() to\nprevent queuing packets to an unregistering device.\n\nHowever, this creates a TOCTOU race window.\n\nA lockless transmitter (like veth_xmit) can pass\nthe check before dev_close() clears IFF_UP. If the transmitter is then\ndelayed, flush_all_backlogs() can run and finish before the transmitter\ngrabs the backlog lock and queues the packet. The packet then escapes\nthe flush and triggers UAF later when processed.\n\nFix this by moving the netif_running() check inside the backlog lock.\nThis serializes the check with the flush work (which also grabs the lock).\nWe then either queue the packet before the flush runs (so it gets flushed),\nor check netif_running() after the flush/close completes (so it gets dropped)."}], "metrics": [{"cvssV3_1": {"version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "baseScore": 9.9, "baseSeverity": "CRITICAL"}, "scenarios": [{"lang": "en", "value": "AV:N - The bug is in the generic per-CPU backlog receive path (`netif_rx`/`netif_receive_skb` -> `enqueue_to_backlog`); packets can originate from remote peers reaching veth/bridge/NIC interfaces, and syzbot reproduced it via network transmit/receive activity during device unregistration.\nAC:L - The attacker controls both racing sides by concurrently flooding packets through a lockless transmitter (e.g. veth) while unregistering the device/netns (e.g. `ip link del` or netns exit); no victim-specific timing or memory layout is required beyond repeatable parallel traffic and teardown.\nPR:L - Triggering veth creation, traffic injection, and netdev/netns teardown requires only `CAP_NET_ADMIN` inside a network namespace, obtainable by an unprivileged local user via user namespaces (`unshare -Urn`); init-namespace root is not required.\nUI:N - Exploitation needs only the attacker's own concurrent packet transmission and interface/netns teardown; no independent action by another user or administrator is required at trigger time.\nS:C - The use-after-free is triggered from within an isolated network namespace yet corrupts host-global kernel routing state (`fib_rules_lookup` on freed namespace/rule data), crossing the container/netns security boundary into the host kernel's integrity and availability.\nC:H - KASAN reported slab-use-after-free in `fib_rules_lookup()` walking `net->rules_ops`; freed namespace/device-associated structures can be reallocated and read through stale pointers, yielding an attacker-influenceable kernel memory read/disclosure primitive.\nI:H - Processing the escaped backlog skb invokes routing through freed `fib_rules_ops` and indirect function pointers (`ops->match`/`ops->action`); UAF on these heap objects enables heap grooming, control-flow hijack, and arbitrary kernel write leading to privilege escalation.\nA:H - Confirmed slab-use-after-free in core packet processing during device unregistration reliably causes kernel oops/panic (syzbot KASAN splat in `fib_rules_lookup()`), and repeated triggering can deny service to the entire host."}]}], "affected": [{"product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/dev.c"], "versions": [{"version": "e9e4dd3267d0c5234c5c0f47440456b10875dec9", "lessThan": "2fface6e0bbd6314d1d9d071abf2c4d67548511c", "status": "affected", "versionType": "git"}, {"version": "e9e4dd3267d0c5234c5c0f47440456b10875dec9", "lessThan": "46762cefe7f4e5bffc1eb467810a7bbb02e461d7", "status": "affected", "versionType": "git"}, {"version": "78b6803a1961369d0b8350ff1f99b7375bbd7a8f", "status": "affected", "versionType": "git"}, {"version": "b5d73d9cdd6be22795499890ea928a6f57ef829c", "status": "affected", "versionType": "git"}, {"version": "f6533fed1bfa842e391ee50f9a9c5e963c71e579", "status": "affected", "versionType": "git"}, {"version": "2095ab2456da766174cda8bc105d7a7b1bc70e16", "status": "affected", "versionType": "git"}, {"version": "f1fdb184aefa8447560e3ea0e605171592ffee41", "status": "affected", "versionType": "git"}, {"version": "f75c8a3015422128ca150e81c730bc2a471b5f4a", "status": "affected", "versionType": "git"}, {"version": "3.2.71", "lessThan": "3.3", "status": "affected", "versionType": "semver"}, {"version": "3.4.111", "lessThan": "3.5", "status": "affected", "versionType": "semver"}, {"version": "3.12.48", "lessThan": "3.13", "status": "affected", "versionType": "semver"}, {"version": "3.14.54", "lessThan": "3.15", "status": "affected", "versionType": "semver"}, {"version": "3.18.22", "lessThan": "3.19", "status": "affected", "versionType": "semver"}, {"version": "4.1.9", "lessThan": "4.2", "status": "affected", "versionType": "semver"}]}, {"product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": ["net/core/dev.c"], "versions": [{"version": "4.2", "status": "affected"}, {"version": "0", "lessThan": "4.2", "status": "unaffected", "versionType": "semver"}, {"version": "7.1.5", "lessThanOrEqual": "7.1.*", "status": "unaffected", "versionType": "semver"}, {"version": "7.2", "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": "4.2", "versionEndExcluding": "7.1.5"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.2", "versionEndExcluding": "7.2"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.2.71"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.4.111"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.12.48"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.14.54"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.18.22"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.1.9"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/2fface6e0bbd6314d1d9d071abf2c4d67548511c"}, {"url": "https://git.kernel.org/stable/c/46762cefe7f4e5bffc1eb467810a7bbb02e461d7"}], "title": "net: serialize netif_running() check in enqueue_to_backlog()", "x_generator": {"engine": "bippy-1.2.0"}}}}

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{"affected": [{"affectedData": [{"defaultStatus": "unaffected", "product": "Linux", "programFiles": ["net/core/dev.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"lessThan": "2fface6e0bbd6314d1d9d071abf2c4d67548511c", "status": "affected", "version": "e9e4dd3267d0c5234c5c0f47440456b10875dec9", "versionType": "git"}, {"lessThan": "46762cefe7f4e5bffc1eb467810a7bbb02e461d7", "status": "affected", "version": "e9e4dd3267d0c5234c5c0f47440456b10875dec9", "versionType": "git"}, {"status": "affected", "version": "78b6803a1961369d0b8350ff1f99b7375bbd7a8f", "versionType": "git"}, {"status": "affected", "version": "b5d73d9cdd6be22795499890ea928a6f57ef829c", "versionType": "git"}, {"status": "affected", "version": "f6533fed1bfa842e391ee50f9a9c5e963c71e579", "versionType": "git"}, {"status": "affected", "version": "2095ab2456da766174cda8bc105d7a7b1bc70e16", "versionType": "git"}, {"status": "affected", "version": "f1fdb184aefa8447560e3ea0e605171592ffee41", "versionType": "git"}, {"status": "affected", "version": "f75c8a3015422128ca150e81c730bc2a471b5f4a", "versionType": "git"}, {"lessThan": "3.3", "status": "affected", "version": "3.2.71", "versionType": "semver"}, {"lessThan": "3.5", "status": "affected", "version": "3.4.111", "versionType": "semver"}, {"lessThan": "3.13", "status": "affected", "version": "3.12.48", "versionType": "semver"}, {"lessThan": "3.15", "status": "affected", "version": "3.14.54", "versionType": "semver"}, {"lessThan": "3.19", "status": "affected", "version": "3.18.22", "versionType": "semver"}, {"lessThan": "4.2", "status": "affected", "version": "4.1.9", "versionType": "semver"}]}, {"defaultStatus": "affected", "product": "Linux", "programFiles": ["net/core/dev.c"], "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "versions": [{"status": "affected", "version": "4.2"}, {"lessThan": "4.2", "status": "unaffected", "version": "0", "versionType": "semver"}, {"lessThanOrEqual": "7.1.*", "status": "unaffected", "version": "7.1.5", "versionType": "semver"}, {"lessThanOrEqual": "*", "status": "unaffected", "version": "7.2", "versionType": "original_commit_for_fix"}]}], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: serialize netif_running() check in enqueue_to_backlog()\n\nSyzbot reported a KASAN slab-use-after-free in fib_rules_lookup().\n\nThe root cause is a race condition where packets can escape the backlog\nflushing during device unregistration (e.g., during netns exit).\n\nCommit e9e4dd3267d0 (\"net: do not process device backlog during unregistration\")\nintroduced a lockless netif_running() check in enqueue_to_backlog() to\nprevent queuing packets to an unregistering device.\n\nHowever, this creates a TOCTOU race window.\n\nA lockless transmitter (like veth_xmit) can pass\nthe check before dev_close() clears IFF_UP. If the transmitter is then\ndelayed, flush_all_backlogs() can run and finish before the transmitter\ngrabs the backlog lock and queues the packet. The packet then escapes\nthe flush and triggers UAF later when processed.\n\nFix this by moving the netif_running() check inside the backlog lock.\nThis serializes the check with the flush work (which also grabs the lock).\nWe then either queue the packet before the flush runs (so it gets flushed),\nor check netif_running() after the flush/close completes (so it gets dropped)."}], "id": "CVE-2026-72493", "lastModified": "2026-08-17T06:19:17.683", "metrics": {"cvssMetricV31": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9.9, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "NONE", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H", "version": "3.1"}, "exploitabilityScore": 3.1, "impactScore": 6.0, "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "type": "Secondary"}]}, "published": "2026-08-15T06:22:23.643", "references": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/2fface6e0bbd6314d1d9d071abf2c4d67548511c"}, {"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "url": "https://git.kernel.org/stable/c/46762cefe7f4e5bffc1eb467810a7bbb02e461d7"}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "vulnStatus": "Received"}

{"bugzilla": {"description": "kernel: net: serialize netif_running() check in enqueue_to_backlog()", "id": "2516670", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2516670"}, "csaw": false, "cvss3": {"cvss3_base_score": "5.5", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "status": "draft"}, "cwe": "CWE-772", "details": ["In the Linux kernel, the following vulnerability has been resolved:\nnet: serialize netif_running() check in enqueue_to_backlog()\nSyzbot reported a KASAN slab-use-after-free in fib_rules_lookup().\nThe root cause is a race condition where packets can escape the backlog\nflushing during device unregistration (e.g., during netns exit).\nCommit e9e4dd3267d0 (\"net: do not process device backlog during unregistration\")\nintroduced a lockless netif_running() check in enqueue_to_backlog() to\nprevent queuing packets to an unregistering device.\nHowever, this creates a TOCTOU race window.\nA lockless transmitter (like veth_xmit) can pass\nthe check before dev_close() clears IFF_UP. If the transmitter is then\ndelayed, flush_all_backlogs() can run and finish before the transmitter\ngrabs the backlog lock and queues the packet. The packet then escapes\nthe flush and triggers UAF later when processed.\nFix this by moving the netif_running() check inside the backlog lock.\nThis serializes the check with the flush work (which also grabs the lock).\nWe then either queue the packet before the flush runs (so it gets flushed),\nor check netif_running() after the flush/close completes (so it gets dropped).", "A flaw was found in the Linux kernel's networking subsystem. A race condition, specifically a Time-of-check to time-of-use (TOCTOU) vulnerability, exists during network device unregistration. This allows network packets to be processed after a device has been unregistered, leading to a use-after-free condition. This could potentially result in arbitrary code execution or a denial of service."], "name": "CVE-2026-72493", "public_date": "2026-08-15T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-72493\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-72493\nhttps://lore.kernel.org/linux-cve-announce/2026081539-CVE-2026-72493-c81d@gregkh/T"], "threat_severity": "Moderate"}