CVE-2026-80994

Estado: RecibidaAlta (7.8)—

In the Linux kernel, the following vulnerability has been resolved:

net: openvswitch: fix flow mask use-after-free on flow deletion

The commit in the Fixes tag below made so flow->mask free is scheduled via RCU right after it is removed from the flow table. The pointer stays in the flow structure and it can be accessible while in the same RCU critical section. This is done to avoid requiring ovs_mutex for the ovs_flow_free().

However, while removing the flow during processing of CMD_DEL, we do not take RCU read lock before the removal, and ovs_flow_cmd_fill_info() uses the flow->mask pointer afterwards. The RCU read lock is taken, but it's already late at that point. The comment on that line acknowledges that the lock is cosmetic and doesn't serve a real purpose.

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This leads to use-after-free if the RCU grace period passes between removal and the filling. It is a short race window, but it is there and can lead to a real crash in case memory allocation for the info takes a bit longer:

ovs_flow_tbl_remove() must be called after the ovs_flow_cmd_fill_info() to avoid this race. This also helps with cleaning up the forced cast and the cosmetic RCU read lock. Before the commit in the Fixes tag the order did not matter as long as the flow object itself was not freed.

A wider RCU critical section could be another option, but we have a GFP_KERNEL allocation in the way.

Reported by Trend Micro's Zero Day Initiative as ZDI-CAN-32042.

Detalles técnicos trazas, registros y código del informe original

 BUG: KASAN: slab-use-after-free in __ovs_nla_put_key
             net/openvswitch/flow_netlink.c:1996
 BUG: KASAN: slab-use-after-free in ovs_nla_put_key+0x2463/0x2e30
             net/openvswitch/flow_netlink.c:2250
 Read of size 4 at addr ffff88801ee89970 by task ovs_flow_del_ec/9487

 Call Trace:
  <TASK>
  __ovs_nla_put_key net/openvswitch/flow_netlink.c:1996
  ovs_nla_put_key+0x2463/0x2e30 net/openvswitch/flow_netlink.c:2250
  ovs_flow_cmd_fill_info+0x420/0x9c0 net/openvswitch/datapath.c:930
  ovs_flow_cmd_del+0x53a/0x970 net/openvswitch/datapath.c:1467
  ...
  netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556
  </TASK>

 Allocated by task 9487:
  mask_alloc net/openvswitch/flow_table.c:967
  flow_mask_insert net/openvswitch/flow_table.c:1012
  ovs_flow_tbl_insert+0xea2/0x1a90 net/openvswitch/flow_table.c:1084
  ovs_flow_cmd_new+0x7e3/0xd90 net/openvswitch/datapath.c:1086
  ...
  netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556

 Freed by task 9485:
  rcu_free_sheaf+0x1e/0x100 mm/slub.c:5978
  rcu_do_batch kernel/rcu/tree.c:2645
  rcu_core+0x59c/0x10c0 kernel/rcu/tree.c:2897
  handle_softirqs+0x1e4/0x9a0 kernel/softirq.c:622
  ...
  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062

CVSS

Versión: 3.1
Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Puntuación base: 7.8

Probabilidad de explotación (EPSS)

Probabilidad de explotación en los próximos 30 días: 0.17%
Percentil entre todas las CVEs puntuadas: 6
Fecha de la puntuación: 5/10/2026

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

ExplotaciónT1068 Exploitation for Privilege Escalationprivilege escalation85 %
Impacto principalT1499.004 Application or System Exploitationimpact75 %
Impacto secundarioT1005 Data from Local Systemcollection65 %

Vulnerabilidad local (AV:L, PR:L) en kernel Linux con impacto de disponibilidad (crash) por use-after-free. Escalada de privilegios potencial tras crash del demonio OVS con acceso kernel.

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Threat Intelligence Program Filter Network Traffic Execution Prevention Application Isolation and Sandboxing Exploit Protection Update Software

Tecnologías afectadas (1)

⚠ Inferidas por IA a partir de la descripción — NVD aún no ha analizado esta CVE; no son CPE verificados.

Linux — Linux Kernel^AI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-80994",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
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        "impactScore": 5.9,
        "exploitabilityScore": 1.8
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              "version": "6.12.109",
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  "published": "2026-09-11T20:19:06.357",
  "references": [
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      "url": "https://git.kernel.org/stable/c/0ba5cbc2f049af94ec94ff6f64958545efc5eaa2",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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    {
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: openvswitch: fix flow mask use-after-free on flow deletion\n\nThe commit in the Fixes tag below made so flow->mask free is scheduled\nvia RCU right after it is removed from the flow table.  The pointer\nstays in the flow structure and it can be accessible while in the same\nRCU critical section.  This is done to avoid requiring ovs_mutex for\nthe ovs_flow_free().\n\nHowever, while removing the flow during processing of CMD_DEL, we do\nnot take RCU read lock before the removal, and ovs_flow_cmd_fill_info()\nuses the flow->mask pointer afterwards.  The RCU read lock is taken,\nbut it's already late at that point.  The comment on that line\nacknowledges that the lock is cosmetic and doesn't serve a real purpose.\n\nThis leads to use-after-free if the RCU grace period passes between\nremoval and the filling.  It is a short race window, but it is there\nand can lead to a real crash in case memory allocation for the info\ntakes a bit longer:\n\n BUG: KASAN: slab-use-after-free in __ovs_nla_put_key\n             net/openvswitch/flow_netlink.c:1996\n BUG: KASAN: slab-use-after-free in ovs_nla_put_key+0x2463/0x2e30\n             net/openvswitch/flow_netlink.c:2250\n Read of size 4 at addr ffff88801ee89970 by task ovs_flow_del_ec/9487\n\n Call Trace:\n  <TASK>\n  __ovs_nla_put_key net/openvswitch/flow_netlink.c:1996\n  ovs_nla_put_key+0x2463/0x2e30 net/openvswitch/flow_netlink.c:2250\n  ovs_flow_cmd_fill_info+0x420/0x9c0 net/openvswitch/datapath.c:930\n  ovs_flow_cmd_del+0x53a/0x970 net/openvswitch/datapath.c:1467\n  ...\n  netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556\n  </TASK>\n\n Allocated by task 9487:\n  mask_alloc net/openvswitch/flow_table.c:967\n  flow_mask_insert net/openvswitch/flow_table.c:1012\n  ovs_flow_tbl_insert+0xea2/0x1a90 net/openvswitch/flow_table.c:1084\n  ovs_flow_cmd_new+0x7e3/0xd90 net/openvswitch/datapath.c:1086\n  ...\n  netlink_rcv_skb+0x156/0x420 net/netlink/af_netlink.c:2556\n\n Freed by task 9485:\n  rcu_free_sheaf+0x1e/0x100 mm/slub.c:5978\n  rcu_do_batch kernel/rcu/tree.c:2645\n  rcu_core+0x59c/0x10c0 kernel/rcu/tree.c:2897\n  handle_softirqs+0x1e4/0x9a0 kernel/softirq.c:622\n  ...\n  instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062\n\novs_flow_tbl_remove() must be called after the ovs_flow_cmd_fill_info()\nto avoid this race.  This also helps with cleaning up the forced cast\nand the cosmetic RCU read lock.  Before the commit in the Fixes tag the\norder did not matter as long as the flow object itself was not freed.\n\nA wider RCU critical section could be another option, but we have a\nGFP_KERNEL allocation in the way.\n\nReported by Trend Micro's Zero Day Initiative as ZDI-CAN-32042."
    }
  ],
  "lastModified": "2026-09-14T13:18:54.043",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}