{ "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-2026-46099", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2026-46099", "idYear": 2026, "status": "PUBLISHED", "publishedAt": "2026-05-27T12:59:04.628Z", "updatedAt": "2026-10-19T19:26:43.421Z", "importedAt": "2026-10-24T01:58:14.884Z", "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: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix NOREF dst use in seg6 and rpl lwtunnels\n\nseg6_input_core() and rpl_input() call ip6_route_input() which sets a\nNOREF dst on the skb, then pass it to dst_cache_set_ip6() invoking\ndst_hold() unconditionally.\nOn PREEMPT_RT, ksoftirqd is preemptible and a higher-priority task can\nrelease the underlying pcpu_rt between the lookup and the caching\nthrough a concurrent FIB lookup on a shared nexthop.\nSimplified race sequence:\n\n ksoftirqd/X higher-prio task (same CPU X)\n ----------- --------------------------------\n seg6_input_core(,skb)/rpl_input(skb)\n dst_cache_get()\n -> miss\n ip6_route_input(skb)\n -> ip6_pol_route(,skb,flags)\n [RT6_LOOKUP_F_DST_NOREF in flags]\n -> FIB lookup resolves fib6_nh\n [nhid=N route]\n -> rt6_make_pcpu_route()\n [creates pcpu_rt, refcount=1]\n pcpu_rt->sernum = fib6_sernum\n [fib6_sernum=W]\n -> cmpxchg(fib6_nh.rt6i_pcpu,\n NULL, pcpu_rt)\n [slot was empty, store succeeds]\n -> skb_dst_set_noref(skb, dst)\n [dst is pcpu_rt, refcount still 1]\n\n rt_genid_bump_ipv6()\n -> bumps fib6_sernum\n [fib6_sernum from W to Z]\n ip6_route_output()\n -> ip6_pol_route()\n -> FIB lookup resolves fib6_nh\n [nhid=N]\n -> rt6_get_pcpu_route()\n pcpu_rt->sernum != fib6_sernum\n [W <> Z, stale]\n -> prev = xchg(rt6i_pcpu, NULL)\n -> dst_release(prev)\n [prev is pcpu_rt,\n refcount 1->0, dead]\n\n dst = skb_dst(skb)\n [dst is the dead pcpu_rt]\n dst_cache_set_ip6(dst)\n -> dst_hold() on dead dst\n -> WARN / use-after-free\n\nFor the race to occur, ksoftirqd must be preemptible (PREEMPT_RT without\nPREEMPT_RT_NEEDS_BH_LOCK) and a concurrent task must be able to release\nthe pcpu_rt. Shared nexthop objects provide such a path, as two routes\npointing to the same nhid share the same fib6_nh and its rt6i_pcpu\nentry.\n\nFix seg6_input_core() and rpl_input() by calling skb_dst_force() after\nip6_route_input() to force the NOREF dst into a refcounted one before\ncaching.\nThe output path is not affected as ip6_route_output() already returns a\nrefcounted dst.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "51fef5a7c4d160839199e941929456ba21ddf73c" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "b258b849a580285a1692e782ebc902b44c884a71" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "6bd17925bd6866027a6555db17905b9fc073d38d" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "52f9db67f8f35f436366cf4980b4f0a2583d0ef0" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "b778b6d095421619c331fd2d7751143cd5387103" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "9dd5481f960e337b81d7dfe429529495c1c481c0" }, { "version": "af4a2209b1344939eaac11f269c261d347cbc3ee", "status": "affected", "versionType": "git", "lessThan": "f9c52a6ba9780bd27e0bf4c044fd91c13c778b6e" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "4.12", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "4.12" }, { "version": "5.15.209", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.15.*" }, { "version": "6.1.175", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.1.*" }, { "version": "6.6.140", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.6.*" }, { "version": "6.12.86", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.12.*" }, { "version": "6.18.27", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "6.18.*" }, { "version": "7.0.4", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "7.0.*" }, { "version": "7.1", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }