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CVE-2026-74489 (GCVE-0-2026-74489)

Vulnerability from cvelistv5 – Published: 2026-08-15 12:27 – Updated: 2026-08-17 05:47
VLAI
Title
wifi: mac80211: fix tid_tx use-after-free on BA session stop
Summary
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: 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); 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. 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: 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 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]
Severity
8.8 (High)
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 98acd4c1d9f7dc9c426e840c16e81b57315ff84b , < 09fc36eec7841cdf732f4db39855e0c73bd075cc (git)
Affected: 98acd4c1d9f7dc9c426e840c16e81b57315ff84b , < 2f067f5a450ea07efd249142a11d940a068fe29c (git)
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Linux Linux Affected: 7.1
Unaffected: 0 , < 7.1 (semver)
Unaffected: 7.1.8 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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{
  "containers": {
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/mac80211/agg-tx.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "09fc36eec7841cdf732f4db39855e0c73bd075cc",
              "status": "affected",
              "version": "98acd4c1d9f7dc9c426e840c16e81b57315ff84b",
              "versionType": "git"
            },
            {
              "lessThan": "2f067f5a450ea07efd249142a11d940a068fe29c",
              "status": "affected",
              "version": "98acd4c1d9f7dc9c426e840c16e81b57315ff84b",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "net/mac80211/agg-tx.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "7.1"
            },
            {
              "lessThan": "7.1",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.1.*",
              "status": "unaffected",
              "version": "7.1.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.1.8",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "7.2",
                  "versionStartIncluding": "7.1",
                  "vulnerable": true
                }
              ],
              "negate": false,
              "operator": "OR"
            }
          ]
        }
      ],
      "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-\u003endp after dropping\nsta-\u003elock:\n\n\tieee80211_remove_tid_tx(sta, tid);\t/* kfree_rcu(tid_tx, rcu_head) */\n\t...\n\tspin_unlock_bh(\u0026sta-\u003elock);\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-\u003endp);\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\u0027s DELBA.\n\nRead ndp into a local before the session is freed, while sta-\u003elock is still\nheld. tid_tx-\u003endp 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-\u003endp 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]"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 8.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:A - The bug is in mac80211 WiFi block-ack teardown; an adjacent 802.11 peer with an active TX BA session can drive AGG_STOP_LOCAL_REQUEST via negotiated session-idle timeouts, PTK rekey, or link conditions that cause local session stop.\nAC:L - This is a slab use-after-free where RCU can free tid_tx between ieee80211_remove_tid_tx() and the post-unlock tid_tx-\u003endp read; the commit reproduced it reliably, and an attacker can repeatedly trigger local BA teardown to hit the race window.\nPR:N - Exploitation requires no Linux user or administrator privileges on the victim, only normal 802.11 association as a WiFi peer to maintain a block-ack session that later undergoes local teardown.\nUI:N - No victim interaction beyond routine WiFi connectivity is needed; session-idle timers, rekey, and driver-initiated local BA stop can fire from background wireless activity without the user performing a specific action.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the host kernel; it does not cross a VM, IOMMU, or sandbox security boundary.\nC:H - Reading tid_tx-\u003endp after kfree_rcu() is a slab use-after-free of a kernel heap object, which can disclose or infer kernel memory contents and support further exploitation primitives.\nI:H - Use-after-free of tid_ampdu_tx enables heap corruption and control of freed object contents, which can be leveraged for arbitrary kernel writes or code execution beyond the single-byte ndp read.\nA:H - The freed-object dereference can cause kernel oops/panic; KASAN reported slab-use-after-free in ieee80211_stop_tx_ba_cb during BA session stop, and UAFs in mac80211 commonly crash the system."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T05:47:46.250Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/09fc36eec7841cdf732f4db39855e0c73bd075cc"
        },
        {
          "url": "https://git.kernel.org/stable/c/2f067f5a450ea07efd249142a11d940a068fe29c"
        }
      ],
      "title": "wifi: mac80211: fix tid_tx use-after-free on BA session stop",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-74489",
    "datePublished": "2026-08-15T12:27:19.505Z",
    "dateReserved": "2026-08-15T05:44:03.905Z",
    "dateUpdated": "2026-08-17T05:47:46.250Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-74489",
      "date": "2026-09-05",
      "epss": "0.00218",
      "percentile": "0.12211"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2026-74489\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2026-08-15T13:17:53.813\",\"lastModified\":\"2026-08-17T06:19:45.170\",\"vulnStatus\":\"Received\",\"cveTags\":[],\"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-\u003endp after dropping\\nsta-\u003elock:\\n\\n\\tieee80211_remove_tid_tx(sta, tid);\\t/* kfree_rcu(tid_tx, rcu_head) */\\n\\t...\\n\\tspin_unlock_bh(\u0026sta-\u003elock);\\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-\u003endp);\\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\u0027s DELBA.\\n\\nRead ndp into a local before the session is freed, while sta-\u003elock is still\\nheld. tid_tx-\u003endp 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-\u003endp 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]\"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/mac80211/agg-tx.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"98acd4c1d9f7dc9c426e840c16e81b57315ff84b\",\"lessThan\":\"09fc36eec7841cdf732f4db39855e0c73bd075cc\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"98acd4c1d9f7dc9c426e840c16e81b57315ff84b\",\"lessThan\":\"2f067f5a450ea07efd249142a11d940a068fe29c\",\"versionType\":\"git\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/mac80211/agg-tx.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"7.1\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"7.1\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.1.8\",\"lessThanOrEqual\":\"7.1.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"7.2\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H\",\"baseScore\":8.8,\"baseSeverity\":\"HIGH\",\"attackVector\":\"ADJACENT_NETWORK\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"NONE\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"HIGH\",\"integrityImpact\":\"HIGH\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":2.8,\"impactScore\":5.9}]},\"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\"}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-20T20:53:59+00:00",
      "cve": "CVE-2026-74489",
      "id": "CVE-2026-74489",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "198",
      "product_status:known_not_affected": "76",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: wifi: mac80211: fix tid_tx use-after-free on BA session stop",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-74489.json",
      "version": "3"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
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  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.