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CVE-2026-74489

Estado: RecibidaAlta (8.8)—

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

wifi: mac80211: fix tid_tx use-after-free on BA session stop

ieee80211_stop_tx_ba_cb() hands tid_tx to kfree_rcu() through ieee80211_remove_tid_tx(), and then reads tid_tx->ndp after dropping sta->lock:

That read is not covered by an RCU read-side critical section, and it runs in preemptible process context: both callers hold the wiphy mutex, reaching it either from the ieee80211_ba_session_work() wiphy work or from ieee80211_sta_tear_down_BA_sessions() during station teardown. Softirqs can run in that window too, both from the local_bh_enable() that ends ieee80211_agg_start_txq() and from any interrupt exit, so the RCU callback can free tid_tx before the read.

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Driving the function from a test module with the grace period forced into that window, KASAN reports the read, and the free arrives on the ordinary RCU softirq path:

send_delba is only set when tx_stop is set, which happens for AGG_STOP_LOCAL_REQUEST alone, so this is reached on local teardown - session idle timeout, PTK rekey, suspend, HW reconfig - and not from a peer's DELBA.

Read ndp into a local before the session is freed, while sta->lock is still held. tid_tx->ndp has a single writer, in ieee80211_tx_ba_session_handle_start(), which cannot run concurrently here: both paths are serialised by the wiphy mutex, and the session is already marked HT_AGG_STATE_STOPPING at this point. tid_tx->ndp is also the only tid_tx dereference left after ieee80211_remove_tid_tx() in this function.

[move/change the comment a bit to be more general not just on ndp, initialize ndp directly]

Detalles técnicos trazas, registros y código del informe original
	ieee80211_remove_tid_tx(sta, tid);	/* kfree_rcu(tid_tx, rcu_head) */
	...
	spin_unlock_bh(&sta->lock);

	if (start_txq)
		ieee80211_agg_start_txq(sta, tid, false);

	if (send_delba)
		ieee80211_send_delba(..., tid_tx->ndp);

  BUG: KASAN: slab-use-after-free in ieee80211_stop_tx_ba_cb+0x3cd/0x400
  Read of size 1 at addr ffff888002b9f52e by task kworker/0:1/10
  [...]
  Freed by task 57:
   __kasan_slab_free+0x47/0x70
   __rcu_free_sheaf_prepare+0x70/0x250
   rcu_free_sheaf_nobarn+0x18/0x40
   rcu_core+0x426/0x1310
   handle_softirqs+0x144/0x590
   __irq_exit_rcu+0xea/0x150
   irq_exit_rcu+0x9/0x20
   sysvec_apic_timer_interrupt+0x6b/0x80
   asm_sysvec_apic_timer_interrupt+0x1a/0x20

CVSS

Probabilidad de explotación (EPSS)

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.

Use-after-free en red adyacente (AV:A) en mac80211 WiFi permite DoS o escalada; acceso local también posible post-explotación en teardown de sesión BA.

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 ProgramApplication Isolation and SandboxingExploit ProtectionUpdate SoftwareVulnerability ScanningPrivileged Account Management

Tecnologías afectadas (1)

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

Linux — Linux KernelAI

Referencias

JSON original (NVD)

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{
  "id": "CVE-2026-74489",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 8.8,
          "attackVector": "ADJACENT_NETWORK",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 2.8
      }
    ]
  },
  "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": "98acd4c1d9f7dc9c426e840c16e81b57315ff84b",
              "lessThan": "09fc36eec7841cdf732f4db39855e0c73bd075cc",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "98acd4c1d9f7dc9c426e840c16e81b57315ff84b",
              "lessThan": "2f067f5a450ea07efd249142a11d940a068fe29c",
              "versionType": "git"
            }
          ],
          "programFiles": [
            "net/mac80211/agg-tx.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "product": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "status": "unaffected",
              "version": "0",
              "lessThan": "7.1",
              "versionType": "semver"
            },
            {
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver",
              "lessThanOrEqual": "7.1.*"
            },
            {
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "net/mac80211/agg-tx.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2026-08-15T13:17:53.813",
  "references": [
    {
      "url": "https://git.kernel.org/stable/c/09fc36eec7841cdf732f4db39855e0c73bd075cc",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    },
    {
      "url": "https://git.kernel.org/stable/c/2f067f5a450ea07efd249142a11d940a068fe29c",
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "vulnStatus": "Received",
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: mac80211: fix tid_tx use-after-free on BA session stop\n\nieee80211_stop_tx_ba_cb() hands tid_tx to kfree_rcu() through\nieee80211_remove_tid_tx(), and then reads tid_tx->ndp after dropping\nsta->lock:\n\n\tieee80211_remove_tid_tx(sta, tid);\t/* kfree_rcu(tid_tx, rcu_head) */\n\t...\n\tspin_unlock_bh(&sta->lock);\n\n\tif (start_txq)\n\t\tieee80211_agg_start_txq(sta, tid, false);\n\n\tif (send_delba)\n\t\tieee80211_send_delba(..., tid_tx->ndp);\n\nThat read is not covered by an RCU read-side critical section, and it runs\nin preemptible process context: both callers hold the wiphy mutex, reaching\nit either from the ieee80211_ba_session_work() wiphy work or from\nieee80211_sta_tear_down_BA_sessions() during station teardown.\nSoftirqs can run in that window too, both from the local_bh_enable() that\nends ieee80211_agg_start_txq() and from any interrupt exit, so the RCU\ncallback can free tid_tx before the read.\n\nDriving the function from a test module with the grace period forced into\nthat window, KASAN reports the read, and the free arrives on the ordinary\nRCU softirq path:\n\n  BUG: KASAN: slab-use-after-free in ieee80211_stop_tx_ba_cb+0x3cd/0x400\n  Read of size 1 at addr ffff888002b9f52e by task kworker/0:1/10\n  [...]\n  Freed by task 57:\n   __kasan_slab_free+0x47/0x70\n   __rcu_free_sheaf_prepare+0x70/0x250\n   rcu_free_sheaf_nobarn+0x18/0x40\n   rcu_core+0x426/0x1310\n   handle_softirqs+0x144/0x590\n   __irq_exit_rcu+0xea/0x150\n   irq_exit_rcu+0x9/0x20\n   sysvec_apic_timer_interrupt+0x6b/0x80\n   asm_sysvec_apic_timer_interrupt+0x1a/0x20\n\nsend_delba is only set when tx_stop is set, which happens for\nAGG_STOP_LOCAL_REQUEST alone, so this is reached on local teardown -\nsession idle timeout, PTK rekey, suspend, HW reconfig - and not from a\npeer's DELBA.\n\nRead ndp into a local before the session is freed, while sta->lock is still\nheld. tid_tx->ndp has a single writer, in\nieee80211_tx_ba_session_handle_start(), which cannot run concurrently here:\nboth paths are serialised by the wiphy mutex, and the session is already\nmarked HT_AGG_STATE_STOPPING at this point. tid_tx->ndp is also the only\ntid_tx dereference left after ieee80211_remove_tid_tx() in this function.\n\n[move/change the comment a bit to be more general not just on ndp,\n initialize ndp directly]"
    }
  ],
  "lastModified": "2026-08-17T06:19:45.170",
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}