CVE-2026-43050

{"id": "CVE-2026-43050", "cveTags": [], "metrics": {"ssvcV203": [{"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "ssvcData": {"id": "CVE-2026-43050", "role": "CISA Coordinator", "options": [{"exploitation": "none"}, {"automatable": "no"}, {"technicalImpact": "partial"}], "version": "2.0.3", "timestamp": "2026-11-06T15:27:14.542294Z"}}], "cvssMetricV31": [{"type": "Primary", "source": "nvd@nist.gov", "cvssData": {"scope": "UNCHANGED", "version": "3.1", "baseScore": 7.0, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "HIGH", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 5.9, "exploitabilityScore": 1.0}]}, "affected": [{"source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "affectedData": [{"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3e8b25f32f2f35549d03d77da030a24a45bdef5b", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "750a33f417f3d196b86375f8d9f8938bacf130fe", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "317843d5355062020649124eb4a0d7acbcc3f53e", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "b256d055da47258e63f8b40965f276c5f23d229a", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "3989740fa4978e1d2d51ecc62be1b01093e104ad", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "abc10f85a3965ac14b9ed7ad3e67b35604a63aa3", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "5fbbb1ff936d7ff9528d929c1549977e8123d8a8", "versionType": "git"}, {"status": "affected", "version": "1da177e4c3f41524e886b7f1b8a0c1fc7321cac2", "lessThan": "922814879542c2e397b0e9641fd36b8202a8e555", "versionType": "git"}], "programFiles": ["net/atm/lec.c", "net/atm/lec.h"], "defaultStatus": "unaffected"}, {"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "vendor": "Linux", "product": "Linux", "versions": [{"status": "affected", "version": "2.6.12"}, {"status": "unaffected", "version": "0", "lessThan": "2.6.12", "versionType": "semver"}, {"status": "unaffected", "version": "5.10.253", "versionType": "semver", "lessThanOrEqual": "5.10.*"}, {"status": "unaffected", "version": "5.15.203", "versionType": "semver", "lessThanOrEqual": "5.15.*"}, {"status": "unaffected", "version": "6.1.168", "versionType": "semver", "lessThanOrEqual": "6.1.*"}, {"status": "unaffected", "version": "6.6.134", "versionType": "semver", "lessThanOrEqual": "6.6.*"}, {"status": "unaffected", "version": "6.12.81", "versionType": "semver", "lessThanOrEqual": "6.12.*"}, {"status": "unaffected", "version": "6.18.22", "versionType": "semver", "lessThanOrEqual": "6.18.*"}, {"status": "unaffected", "version": "6.19.12", "versionType": "semver", "lessThanOrEqual": "6.19.*"}, {"status": "unaffected", "version": "7.0", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*"}], "programFiles": ["net/atm/lec.c", "net/atm/lec.h"], "defaultStatus": "affected"}]}], "published": "2026-05-01T15:16:51.403", "references": [{"url": "https://git.kernel.org/stable/c/317843d5355062020649124eb4a0d7acbcc3f53e", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/3989740fa4978e1d2d51ecc62be1b01093e104ad", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/3e8b25f32f2f35549d03d77da030a24a45bdef5b", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/5fbbb1ff936d7ff9528d929c1549977e8123d8a8", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/750a33f417f3d196b86375f8d9f8938bacf130fe", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/922814879542c2e397b0e9641fd36b8202a8e555", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/abc10f85a3965ac14b9ed7ad3e67b35604a63aa3", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}, {"url": "https://git.kernel.org/stable/c/b256d055da47258e63f8b40965f276c5f23d229a", "tags": ["Patch"], "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Primary", "source": "nvd@nist.gov", "description": [{"lang": "en", "value": "CWE-416"}]}], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\natm: lec: fix use-after-free in sock_def_readable()\n\nA race condition exists between lec_atm_close() setting priv->lecd\nto NULL and concurrent access to priv->lecd in send_to_lecd(),\nlec_handle_bridge(), and lec_atm_send(). When the socket is freed\nvia RCU while another thread is still using it, a use-after-free\noccurs in sock_def_readable() when accessing the socket's wait queue.\n\nThe root cause is that lec_atm_close() clears priv->lecd without\nany synchronization, while callers dereference priv->lecd without\nany protection against concurrent teardown.\n\nFix this by converting priv->lecd to an RCU-protected pointer:\n- Mark priv->lecd as __rcu in lec.h\n- Use rcu_assign_pointer() in lec_atm_close() and lecd_attach()\n for safe pointer assignment\n- Use rcu_access_pointer() for NULL checks that do not dereference\n the pointer in lec_start_xmit(), lec_push(), send_to_lecd() and\n lecd_attach()\n- Use rcu_read_lock/rcu_dereference/rcu_read_unlock in send_to_lecd(),\n lec_handle_bridge() and lec_atm_send() to safely access lecd\n- Use rcu_assign_pointer() followed by synchronize_rcu() in\n lec_atm_close() to ensure all readers have completed before\n proceeding. This is safe since lec_atm_close() is called from\n vcc_release() which holds lock_sock(), a sleeping lock.\n- Remove the manual sk_receive_queue drain from lec_atm_close()\n since vcc_destroy_socket() already drains it after lec_atm_close()\n returns.\n\nv2: Switch from spinlock + sock_hold/put approach to RCU to properly\n fix the race. The v1 spinlock approach had two issues pointed out\n by Eric Dumazet:\n 1. priv->lecd was still accessed directly after releasing the\n lock instead of using a local copy.\n 2. The spinlock did not prevent packets being queued after\n lec_atm_close() drains sk_receive_queue since timer and\n workqueue paths bypass netif_stop_queue().\n\nNote: Syzbot patch testing was attempted but the test VM terminated\n unexpectedly with \"Connection to localhost closed by remote host\",\n likely due to a QEMU AHCI emulation issue unrelated to this fix.\n Compile testing with \"make W=1 net/atm/lec.o\" passes cleanly."}, {"lang": "es", "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\natm: lec: corregir uso despu\u00e9s de liberaci\u00f3n en sock_def_readable()\n\nExiste una condici\u00f3n de carrera entre lec_atm_close() estableciendo priv -> lecd a NULL y el acceso concurrente a priv -> lecd en send_to_lecd(), lec_handle_bridge() y lec_atm_send(). Cuando el socket es liberado a trav\u00e9s de RCU mientras otro hilo todav\u00eda lo est\u00e1 usando, ocurre un uso despu\u00e9s de liberaci\u00f3n en sock_def_readable() al acceder a la cola de espera del socket.\n\nLa causa ra\u00edz es que lec_atm_close() borra priv -> lecd sin ninguna sincronizaci\u00f3n, mientras que las funciones que lo llaman desreferencian priv -> lecd sin ninguna protecci\u00f3n contra la desestructuraci\u00f3n concurrente.\n\nCorregir esto convirtiendo priv -> lecd en un puntero protegido por RCU:\n- Marcar priv -> lecd como __rcu en lec.h\n- Usar rcu_assign_pointer() en lec_atm_close() y lecd_attach() para una asignaci\u00f3n segura de puntero\n- Usar rcu_access_pointer() para comprobaciones de NULL que no desreferencian el puntero en lec_start_xmit(), lec_push(), send_to_lecd() y lecd_attach()\n- Usar rcu_read_lock/rcu_dereference/rcu_read_unlock en send_to_lecd(), lec_handle_bridge() y lec_atm_send() para acceder a lecd de forma segura\n- Usar rcu_assign_pointer() seguido de synchronize_rcu() en lec_atm_close() para asegurar que todos los lectores hayan completado antes de continuar. Esto es seguro ya que lec_atm_close() es llamado desde vcc_release() que mantiene lock_sock(), un bloqueo de suspensi\u00f3n.\n- Eliminar el vaciado manual de sk_receive_queue de lec_atm_close() ya que vcc_destroy_socket() ya lo vac\u00eda despu\u00e9s de que lec_atm_close() retorna.\n\nv2: Cambiar del enfoque de spinlock + sock_hold/put a RCU para corregir adecuadamente la condici\u00f3n de carrera. El enfoque de spinlock de la v1 ten\u00eda dos problemas se\u00f1alados por Eric Dumazet:\n1. Se segu\u00eda accediendo a priv -> lecd directamente despu\u00e9s de liberar el bloqueo en lugar de usar una copia local.\n2. El spinlock no evitaba que los paquetes se encolaran despu\u00e9s de que lec_atm_close() vaciara sk_receive_queue, ya que las rutas de temporizador y workqueue eluden netif_stop_queue().\n\nNota: Se intent\u00f3 la prueba de parche de Syzbot, pero la VM de prueba termin\u00f3 inesperadamente con \u2019Connection to localhost closed by remote host\u2019, probablemente debido a un problema de emulaci\u00f3n AHCI de QEMU no relacionado con esta correcci\u00f3n. La prueba de compilaci\u00f3n con \u2019make W=1 net/atm/lec.o\u2019 pasa limpiamente."}], "lastModified": "2026-11-11T23:10:00.263", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "5F0E43E1-33E5-4828-9B4A-F710AF2E7217", "versionEndExcluding": "5.10.253", "versionStartIncluding": "2.6.12.1"}, {"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": "E2DDDCA1-6DAB-4018-B920-8F045DDD8D3B", "versionEndExcluding": "6.1.168", "versionStartIncluding": "5.16"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F56F925B-BAF8-4F4B-B62F-1496AF19A307", "versionEndExcluding": "6.6.134", "versionStartIncluding": "6.2"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6EF80433-B33B-43C5-8E64-0FA7B8DCE1BC", "versionEndExcluding": "6.12.81", "versionStartIncluding": "6.7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "C9DF8BCE-36D3-475D-9D21-19E4F02F9029", "versionEndExcluding": "6.18.22", "versionStartIncluding": "6.13"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0A2B9540-02D5-41B4-B16A-82AF66FD4F36", "versionEndExcluding": "6.19.12", "versionStartIncluding": "6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:-:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6F62EECE-8FB1-4D57-85D8-CB9E23CF313C"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4F76C298-81DC-43E4-8FC9-DC005A2116EF"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0AB349B2-3F78-4197-882B-90ADB3BF645A"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "6AC88830-A9BC-4607-B572-A4B502FC9FD0"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:2.6.12:rc5:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "476CB3A5-D022-4F13-AAEF-CB6A5785516A"}, {"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"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "F666C8D8-6538-46D4-B318-87610DE64C34"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:7.0:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "02259FDA-961B-47BC-AE7F-93D7EC6E90C2"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}