CVE-2026-23300

{"id": "CVE-2026-23300", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 5.5, "attackVector": "LOCAL", "baseSeverity": "MEDIUM", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "integrityImpact": "NONE", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "NONE"}, "impactScore": 3.6, "exploitabilityScore": 1.8}]}, "published": "2026-03-25T11:16:25.623", "references": [{"url": "https://git.kernel.org/stable/c/21ec92774d1536f71bdc90b0e3d052eff99cf093", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/607e68c1b7c5a30c795571be1906d716e989a644", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/8650db85b4259d2885d2a80fbc2317ce24194133", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b299121e7453d23faddf464087dff513a495b4fc", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b3b5a037d520afe3d5276e653bc0ff516bbda34c", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b5062fc2150614c9ea8a611c2e0cb6e047ebfa3a", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/c11d7c56c2076ee9cd72004f1976fe0734df2ae9", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/f7c9f8e3607440fe39300efbaf46cf7b5eecb23f", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-476"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv6: fix panic when IPv4 route references loopback IPv6 nexthop\n\nWhen a standalone IPv6 nexthop object is created with a loopback device\n(e.g., \"ip -6 nexthop add id 100 dev lo\"), fib6_nh_init() misclassifies\nit as a reject route. This is because nexthop objects have no destination\nprefix (fc_dst=::), causing fib6_is_reject() to match any loopback\nnexthop. The reject path skips fib_nh_common_init(), leaving\nnhc_pcpu_rth_output unallocated. If an IPv4 route later references this\nnexthop, __mkroute_output() dereferences NULL nhc_pcpu_rth_output and\npanics.\n\nSimplify the check in fib6_nh_init() to only match explicit reject\nroutes (RTF_REJECT) instead of using fib6_is_reject(). The loopback\npromotion heuristic in fib6_is_reject() is handled separately by\nip6_route_info_create_nh(). After this change, the three cases behave\nas follows:\n\n1. Explicit reject route (\"ip -6 route add unreachable 2001:db8::/64\"):\n RTF_REJECT is set, enters reject path, skips fib_nh_common_init().\n No behavior change.\n\n2. Implicit loopback reject route (\"ip -6 route add 2001:db8::/32 dev lo\"):\n RTF_REJECT is not set, takes normal path, fib_nh_common_init() is\n called. ip6_route_info_create_nh() still promotes it to reject\n afterward. nhc_pcpu_rth_output is allocated but unused, which is\n harmless.\n\n3. Standalone nexthop object (\"ip -6 nexthop add id 100 dev lo\"):\n RTF_REJECT is not set, takes normal path, fib_nh_common_init() is\n called. nhc_pcpu_rth_output is properly allocated, fixing the crash\n when IPv4 routes reference this nexthop."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nnet: ipv6: corrige el p\u00e1nico cuando una ruta IPv4 referencia un nexthop IPv6 de loopback\n\nCuando se crea un objeto nexthop IPv6 independiente con un dispositivo de loopback (p. ej., 'ip -6 nexthop add id 100 dev lo'), fib6_nh_init() lo clasifica err\u00f3neamente como una ruta de rechazo. Esto se debe a que los objetos nexthop no tienen prefijo de destino (fc_dst=::), lo que hace que fib6_is_reject() coincida con cualquier nexthop de loopback. La ruta de rechazo omite fib_nh_common_init(), dejando nhc_pcpu_rth_output sin asignar. Si una ruta IPv4 referencia posteriormente este nexthop, __mkroute_output() desreferencia nhc_pcpu_rth_output NULL y entra en p\u00e1nico.\n\nSimplificar la verificaci\u00f3n en fib6_nh_init() para que solo coincida con rutas de rechazo expl\u00edcitas (RTF_REJECT) en lugar de usar fib6_is_reject(). La heur\u00edstica de promoci\u00f3n de loopback en fib6_is_reject() se maneja por separado por ip6_route_info_create_nh(). Despu\u00e9s de este cambio, los tres casos se comportan de la siguiente manera:\n\n1. Ruta de rechazo expl\u00edcita ('ip -6 route add unreachable 2001:db8::/64'):\n RTF_REJECT est\u00e1 configurado, entra en la ruta de rechazo, omite fib_nh_common_init().\n Sin cambio de comportamiento.\n\n2. Ruta de rechazo de loopback impl\u00edcita ('ip -6 route add 2001:db8::/32 dev lo'):\n RTF_REJECT no est\u00e1 configurado, toma la ruta normal, se llama a fib_nh_common_init().\n ip6_route_info_create_nh() a\u00fan lo promueve a rechazo posteriormente. nhc_pcpu_rth_output se asigna pero no se usa, lo cual es inofensivo.\n\n3. Objeto nexthop independiente ('ip -6 nexthop add id 100 dev lo'):\n RTF_REJECT no est\u00e1 configurado, toma la ruta normal, se llama a fib_nh_common_init().\n nhc_pcpu_rth_output se asigna correctamente, corrigiendo el fallo cuando las rutas IPv4 referencian este nexthop."}], "lastModified": "2026-05-28T14:46:05.717", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A2D2F803-8C22-4352-AD69-759DA6F15B32", "versionEndExcluding": "5.10.253", "versionStartIncluding": "5.3"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "20DDB3E9-AABF-4107-ADB0-5362AA067045", "versionEndExcluding": "5.15.203", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "2EDC6BAF-B710-4E26-B6AA-D68922EE7B43", "versionEndExcluding": "6.1.167", "versionStartIncluding": "5.16"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C57BB918-DF28-46B3-94F7-144176841267", "versionEndExcluding": "6.6.130", "versionStartIncluding": "6.2"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "B3D12E00-E42D-4056-B354-BAD4903C03A5", "versionEndExcluding": "6.12.77", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "A5E006E4-59C7-43C1-9231-62A72219F2BA", "versionEndExcluding": "6.18.17", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "69245D10-0B71-485E-80C3-A64F077004D3", "versionEndExcluding": "6.19.7", "versionStartIncluding": "6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F253B622-8837-4245-BCE5-A7BF8FC76A16"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4AE85AD8-4641-4E7C-A2F4-305E2CD9EE64"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}