{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2025-38468", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2025-38468", "idYear": 2025, "status": "PUBLISHED", "publishedAt": "2025-07-28T11:12:20.188Z", "updatedAt": "2026-10-15T01:07:21.684Z", "importedAt": "2026-10-24T01:57:34.152Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "net/sched: Return NULL when htb_lookup_leaf encounters an empty rbtree", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet/sched: Return NULL when htb_lookup_leaf encounters an empty rbtree\n\nhtb_lookup_leaf has a BUG_ON that can trigger with the following:\n\ntc qdisc del dev lo root\ntc qdisc add dev lo root handle 1: htb default 1\ntc class add dev lo parent 1: classid 1:1 htb rate 64bit\ntc qdisc add dev lo parent 1:1 handle 2: netem\ntc qdisc add dev lo parent 2:1 handle 3: blackhole\nping -I lo -c1 -W0.001 127.0.0.1\n\nThe root cause is the following:\n\n1. htb_dequeue calls htb_dequeue_tree which calls the dequeue handler on\n the selected leaf qdisc\n2. netem_dequeue calls enqueue on the child qdisc\n3. blackhole_enqueue drops the packet and returns a value that is not\n just NET_XMIT_SUCCESS\n4. Because of this, netem_dequeue calls qdisc_tree_reduce_backlog, and\n since qlen is now 0, it calls htb_qlen_notify -> htb_deactivate ->\n htb_deactiviate_prios -> htb_remove_class_from_row -> htb_safe_rb_erase\n5. As this is the only class in the selected hprio rbtree,\n __rb_change_child in __rb_erase_augmented sets the rb_root pointer to\n NULL\n6. Because blackhole_dequeue returns NULL, netem_dequeue returns NULL,\n which causes htb_dequeue_tree to call htb_lookup_leaf with the same\n hprio rbtree, and fail the BUG_ON\n\nThe function graph for this scenario is shown here:\n 0) | htb_enqueue() {\n 0) + 13.635 us | netem_enqueue();\n 0) 4.719 us | htb_activate_prios();\n 0) # 2249.199 us | }\n 0) | htb_dequeue() {\n 0) 2.355 us | htb_lookup_leaf();\n 0) | netem_dequeue() {\n 0) + 11.061 us | blackhole_enqueue();\n 0) | qdisc_tree_reduce_backlog() {\n 0) | qdisc_lookup_rcu() {\n 0) 1.873 us | qdisc_match_from_root();\n 0) 6.292 us | }\n 0) 1.894 us | htb_search();\n 0) | htb_qlen_notify() {\n 0) 2.655 us | htb_deactivate_prios();\n 0) 6.933 us | }\n 0) + 25.227 us | }\n 0) 1.983 us | blackhole_dequeue();\n 0) + 86.553 us | }\n 0) # 2932.761 us | qdisc_warn_nonwc();\n 0) | htb_lookup_leaf() {\n 0) | BUG_ON();\n ------------------------------------------\n\nThe full original bug report can be seen here [1].\n\nWe can fix this just by returning NULL instead of the BUG_ON,\nas htb_dequeue_tree returns NULL when htb_lookup_leaf returns\nNULL.\n\n[1] https://lore.kernel.org/netdev/pF5XOOIim0IuEfhI-SOxTgRvNoDwuux7UHKnE_Y5-zVd4wmGvNk2ceHjKb8ORnzw0cGwfmVu42g9dL7XyJLf1NEzaztboTWcm0Ogxuojoeo=@willsroot.io/", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "fed3570e548a6c9f95c5f4c9e1a7afc1679fd90d" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "5c0506cd1b1a3b145bda2612bbf7fe78d186c355" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "850226aef8d28a00cf966ef26d2f8f2bff344535" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "890a5d423ef0a7bd13447ceaffad21189f557301" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "7ff2d83ecf2619060f30ecf9fad4f2a700fca344" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "e5c480dc62a3025b8428d4818e722da30ad6804f" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "3691f84269a23f7edd263e9b6edbc27b7ae332f4" }, { "version": "512bb43eb5422ee69a1be05ea0d89dc074fac9a2", "status": "affected", "versionType": "git", "lessThan": "0e1d5d9b5c5966e2e42e298670808590db5ed628" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.29", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.29" }, { "version": "5.4.297", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.241", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.15.190", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.147", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.100", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.40", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.15.8", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.15.*" }, { "version": "6.16", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }