CVE-2025-21809 (GCVE-0-2025-21809)

Vulnerability from cvelistv5 – Published: 2025-02-27 20:01 – Updated: 2026-05-23 15:57
VLAI
Title
rxrpc, afs: Fix peer hash locking vs RCU callback
Summary
In the Linux kernel, the following vulnerability has been resolved: rxrpc, afs: Fix peer hash locking vs RCU callback In its address list, afs now retains pointers to and refs on one or more rxrpc_peer objects. The address list is freed under RCU and at this time, it puts the refs on those peers. Now, when an rxrpc_peer object runs out of refs, it gets removed from the peer hash table and, for that, rxrpc has to take a spinlock. However, it is now being called from afs's RCU cleanup, which takes place in BH context - but it is just taking an ordinary spinlock. The put may also be called from non-BH context, and so there exists the possibility of deadlock if the BH-based RCU cleanup happens whilst the hash spinlock is held. This led to the attached lockdep complaint. Fix this by changing spinlocks of rxnet->peer_hash_lock back to BH-disabling locks. ================================ WARNING: inconsistent lock state 6.13.0-rc5-build2+ #1223 Tainted: G E -------------------------------- inconsistent {SOFTIRQ-ON-W} -> {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810babe228 (&rxnet->peer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180 {SOFTIRQ-ON-W} state was registered at: mark_usage+0x164/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_peer_keepalive_worker+0x144/0x440 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x19b/0x1b0 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 irq event stamp: 972402 hardirqs last enabled at (972402): [<ffffffff8244360e>] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [<ffffffff82443328>] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [<ffffffff810ffbbe>] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [<ffffffff810ffc54>] __irq_exit_rcu+0x44/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&rxnet->peer_hash_lock); <Interrupt> lock(&rxnet->peer_hash_lock); *** DEADLOCK *** 1 lock held by swapper/1/0: #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30 stack backtrace: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G E 6.13.0-rc5-build2+ #1223 Tainted: [E]=UNSIGNED_MODULE Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace: <IRQ> dump_stack_lvl+0x57/0x80 print_usage_bug.part.0+0x227/0x240 valid_state+0x53/0x70 mark_lock_irq+0xa5/0x2f0 mark_lock+0xf7/0x170 mark_usage+0xe1/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_put_peer+0xcb/0x180 afs_free_addrlist+0x46/0x90 [kafs] rcu_do_batch+0x2d2/0x640 rcu_core+0x2f7/0x350 handle_softirqs+0x1ee/0x430 __irq_exit_rcu+0x44/0x110 irq_exit_rcu+0xa/0x30 sysvec_apic_timer_interrupt+0x7f/0xa0 </IRQ>
Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator (v2.0.3)
CWE
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 72904d7b9bfbf2dd146254edea93958bc35bbbfe , < 10ba5a3d57af20e494e0d979d1894260989235dd (git)
Affected: 72904d7b9bfbf2dd146254edea93958bc35bbbfe , < 0e77dd41689637ac4e1b8fe0f27541f373640855 (git)
Affected: 72904d7b9bfbf2dd146254edea93958bc35bbbfe , < 79d458c13056559d49b5e41fbc4b6890e68cf65b (git)
Affected: 056fc740be000d39a7dba700a935f3bbfbc664e6 (git)
Affected: 6.7.3 , < 6.8 (semver)
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Linux Linux Affected: 6.8
Unaffected: 0 , < 6.8 (semver)
Unaffected: 6.12.13 , ≤ 6.12.* (semver)
Unaffected: 6.13.2 , ≤ 6.13.* (semver)
Unaffected: 6.14 , ≤ * (original_commit_for_fix)
Create a notification for this product.
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{
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            "cvssV3_1": {
              "attackComplexity": "LOW",
              "attackVector": "LOCAL",
              "availabilityImpact": "HIGH",
              "baseScore": 5.5,
              "baseSeverity": "MEDIUM",
              "confidentialityImpact": "NONE",
              "integrityImpact": "NONE",
              "privilegesRequired": "LOW",
              "scope": "UNCHANGED",
              "userInteraction": "NONE",
              "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
              "version": "3.1"
            }
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            "other": {
              "content": {
                "id": "CVE-2025-21809",
                "options": [
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                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
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                "role": "CISA Coordinator",
                "timestamp": "2025-10-01T19:28:41.037357Z",
                "version": "2.0.3"
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              "type": "ssvc"
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            "descriptions": [
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                "cweId": "CWE-667",
                "description": "CWE-667 Improper Locking",
                "lang": "en",
                "type": "CWE"
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        "providerMetadata": {
          "dateUpdated": "2025-10-01T19:36:38.646Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
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        "title": "CISA ADP Vulnrichment"
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    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/rxrpc/peer_event.c",
            "net/rxrpc/peer_object.c"
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              "version": "6.7.3",
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          "product": "Linux",
          "programFiles": [
            "net/rxrpc/peer_event.c",
            "net/rxrpc/peer_object.c"
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          "vendor": "Linux",
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              "version": "6.8"
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              "status": "unaffected",
              "version": "0",
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              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.13",
              "versionType": "semver"
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            {
              "lessThanOrEqual": "6.13.*",
              "status": "unaffected",
              "version": "6.13.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.14",
              "versionType": "original_commit_for_fix"
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        }
      ],
      "cpeApplicability": [
        {
          "nodes": [
            {
              "cpeMatch": [
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                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
                  "versionEndExcluding": "6.12.13",
                  "versionStartIncluding": "6.8",
                  "vulnerable": true
                },
                {
                  "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nrxrpc, afs: Fix peer hash locking vs RCU callback\n\nIn its address list, afs now retains pointers to and refs on one or more\nrxrpc_peer objects.  The address list is freed under RCU and at this time,\nit puts the refs on those peers.\n\nNow, when an rxrpc_peer object runs out of refs, it gets removed from the\npeer hash table and, for that, rxrpc has to take a spinlock.  However, it\nis now being called from afs\u0027s RCU cleanup, which takes place in BH\ncontext - but it is just taking an ordinary spinlock.\n\nThe put may also be called from non-BH context, and so there exists the\npossibility of deadlock if the BH-based RCU cleanup happens whilst the hash\nspinlock is held.  This led to the attached lockdep complaint.\n\nFix this by changing spinlocks of rxnet-\u003epeer_hash_lock back to\nBH-disabling locks.\n\n    ================================\n    WARNING: inconsistent lock state\n    6.13.0-rc5-build2+ #1223 Tainted: G            E\n    --------------------------------\n    inconsistent {SOFTIRQ-ON-W} -\u003e {IN-SOFTIRQ-W} usage.\n    swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes:\n    ffff88810babe228 (\u0026rxnet-\u003epeer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180\n    {SOFTIRQ-ON-W} state was registered at:\n      mark_usage+0x164/0x180\n      __lock_acquire+0x544/0x990\n      lock_acquire.part.0+0x103/0x280\n      _raw_spin_lock+0x2f/0x40\n      rxrpc_peer_keepalive_worker+0x144/0x440\n      process_one_work+0x486/0x7c0\n      process_scheduled_works+0x73/0x90\n      worker_thread+0x1c8/0x2a0\n      kthread+0x19b/0x1b0\n      ret_from_fork+0x24/0x40\n      ret_from_fork_asm+0x1a/0x30\n    irq event stamp: 972402\n    hardirqs last  enabled at (972402): [\u003cffffffff8244360e\u003e] _raw_spin_unlock_irqrestore+0x2e/0x50\n    hardirqs last disabled at (972401): [\u003cffffffff82443328\u003e] _raw_spin_lock_irqsave+0x18/0x60\n    softirqs last  enabled at (972300): [\u003cffffffff810ffbbe\u003e] handle_softirqs+0x3ee/0x430\n    softirqs last disabled at (972313): [\u003cffffffff810ffc54\u003e] __irq_exit_rcu+0x44/0x110\n\n    other info that might help us debug this:\n     Possible unsafe locking scenario:\n           CPU0\n           ----\n      lock(\u0026rxnet-\u003epeer_hash_lock);\n      \u003cInterrupt\u003e\n        lock(\u0026rxnet-\u003epeer_hash_lock);\n\n     *** DEADLOCK ***\n    1 lock held by swapper/1/0:\n     #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30\n\n    stack backtrace:\n    CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G            E      6.13.0-rc5-build2+ #1223\n    Tainted: [E]=UNSIGNED_MODULE\n    Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014\n    Call Trace:\n     \u003cIRQ\u003e\n     dump_stack_lvl+0x57/0x80\n     print_usage_bug.part.0+0x227/0x240\n     valid_state+0x53/0x70\n     mark_lock_irq+0xa5/0x2f0\n     mark_lock+0xf7/0x170\n     mark_usage+0xe1/0x180\n     __lock_acquire+0x544/0x990\n     lock_acquire.part.0+0x103/0x280\n     _raw_spin_lock+0x2f/0x40\n     rxrpc_put_peer+0xcb/0x180\n     afs_free_addrlist+0x46/0x90 [kafs]\n     rcu_do_batch+0x2d2/0x640\n     rcu_core+0x2f7/0x350\n     handle_softirqs+0x1ee/0x430\n     __irq_exit_rcu+0x44/0x110\n     irq_exit_rcu+0xa/0x30\n     sysvec_apic_timer_interrupt+0x7f/0xa0\n     \u003c/IRQ\u003e"
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-05-23T15:57:12.005Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/10ba5a3d57af20e494e0d979d1894260989235dd"
        },
        {
          "url": "https://git.kernel.org/stable/c/0e77dd41689637ac4e1b8fe0f27541f373640855"
        },
        {
          "url": "https://git.kernel.org/stable/c/79d458c13056559d49b5e41fbc4b6890e68cf65b"
        }
      ],
      "title": "rxrpc, afs: Fix peer hash locking vs RCU callback",
      "x_generator": {
        "engine": "bippy-1.2.0"
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  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2025-21809",
    "datePublished": "2025-02-27T20:01:00.969Z",
    "dateReserved": "2024-12-29T08:45:45.772Z",
    "dateUpdated": "2026-05-23T15:57:12.005Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2025-21809",
      "date": "2026-07-17",
      "epss": "0.00148",
      "percentile": "0.04454"
    },
    "nvd": "{\"cve\":{\"id\":\"CVE-2025-21809\",\"sourceIdentifier\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"published\":\"2025-02-27T20:16:03.497\",\"lastModified\":\"2026-06-17T08:44:19.777\",\"vulnStatus\":\"Modified\",\"cveTags\":[],\"descriptions\":[{\"lang\":\"en\",\"value\":\"In the Linux kernel, the following vulnerability has been resolved:\\n\\nrxrpc, afs: Fix peer hash locking vs RCU callback\\n\\nIn its address list, afs now retains pointers to and refs on one or more\\nrxrpc_peer objects.  The address list is freed under RCU and at this time,\\nit puts the refs on those peers.\\n\\nNow, when an rxrpc_peer object runs out of refs, it gets removed from the\\npeer hash table and, for that, rxrpc has to take a spinlock.  However, it\\nis now being called from afs\u0027s RCU cleanup, which takes place in BH\\ncontext - but it is just taking an ordinary spinlock.\\n\\nThe put may also be called from non-BH context, and so there exists the\\npossibility of deadlock if the BH-based RCU cleanup happens whilst the hash\\nspinlock is held.  This led to the attached lockdep complaint.\\n\\nFix this by changing spinlocks of rxnet-\u003epeer_hash_lock back to\\nBH-disabling locks.\\n\\n    ================================\\n    WARNING: inconsistent lock state\\n    6.13.0-rc5-build2+ #1223 Tainted: G            E\\n    --------------------------------\\n    inconsistent {SOFTIRQ-ON-W} -\u003e {IN-SOFTIRQ-W} usage.\\n    swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes:\\n    ffff88810babe228 (\u0026rxnet-\u003epeer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180\\n    {SOFTIRQ-ON-W} state was registered at:\\n      mark_usage+0x164/0x180\\n      __lock_acquire+0x544/0x990\\n      lock_acquire.part.0+0x103/0x280\\n      _raw_spin_lock+0x2f/0x40\\n      rxrpc_peer_keepalive_worker+0x144/0x440\\n      process_one_work+0x486/0x7c0\\n      process_scheduled_works+0x73/0x90\\n      worker_thread+0x1c8/0x2a0\\n      kthread+0x19b/0x1b0\\n      ret_from_fork+0x24/0x40\\n      ret_from_fork_asm+0x1a/0x30\\n    irq event stamp: 972402\\n    hardirqs last  enabled at (972402): [\u003cffffffff8244360e\u003e] _raw_spin_unlock_irqrestore+0x2e/0x50\\n    hardirqs last disabled at (972401): [\u003cffffffff82443328\u003e] _raw_spin_lock_irqsave+0x18/0x60\\n    softirqs last  enabled at (972300): [\u003cffffffff810ffbbe\u003e] handle_softirqs+0x3ee/0x430\\n    softirqs last disabled at (972313): [\u003cffffffff810ffc54\u003e] __irq_exit_rcu+0x44/0x110\\n\\n    other info that might help us debug this:\\n     Possible unsafe locking scenario:\\n           CPU0\\n           ----\\n      lock(\u0026rxnet-\u003epeer_hash_lock);\\n      \u003cInterrupt\u003e\\n        lock(\u0026rxnet-\u003epeer_hash_lock);\\n\\n     *** DEADLOCK ***\\n    1 lock held by swapper/1/0:\\n     #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30\\n\\n    stack backtrace:\\n    CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G            E      6.13.0-rc5-build2+ #1223\\n    Tainted: [E]=UNSIGNED_MODULE\\n    Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014\\n    Call Trace:\\n     \u003cIRQ\u003e\\n     dump_stack_lvl+0x57/0x80\\n     print_usage_bug.part.0+0x227/0x240\\n     valid_state+0x53/0x70\\n     mark_lock_irq+0xa5/0x2f0\\n     mark_lock+0xf7/0x170\\n     mark_usage+0xe1/0x180\\n     __lock_acquire+0x544/0x990\\n     lock_acquire.part.0+0x103/0x280\\n     _raw_spin_lock+0x2f/0x40\\n     rxrpc_put_peer+0xcb/0x180\\n     afs_free_addrlist+0x46/0x90 [kafs]\\n     rcu_do_batch+0x2d2/0x640\\n     rcu_core+0x2f7/0x350\\n     handle_softirqs+0x1ee/0x430\\n     __irq_exit_rcu+0x44/0x110\\n     irq_exit_rcu+0xa/0x30\\n     sysvec_apic_timer_interrupt+0x7f/0xa0\\n     \u003c/IRQ\u003e\"},{\"lang\":\"es\",\"value\":\"En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: rxrpc, afs: Fix peer hash blocking vs RCU callback En su lista de direcciones, afs ahora retiene punteros y referencias en uno o m\u00e1s objetos rxrpc_peer. La lista de direcciones se libera bajo RCU y en este momento, pone las referencias en esos pares. Ahora, cuando un objeto rxrpc_peer se queda sin referencias, se elimina de la tabla hash de pares y, para eso, rxrpc tiene que tomar un spinlock. Sin embargo, ahora se est\u00e1 llamando desde la limpieza RCU de afs, que tiene lugar en el contexto BH, pero solo est\u00e1 tomando un spinlock ordinario. La put tambi\u00e9n se puede llamar desde un contexto que no sea BH, por lo que existe la posibilidad de un punto muerto si la limpieza RCU basada en BH ocurre mientras se mantiene el spinlock hash. Esto condujo a la queja adjunta lockdep. Solucione esto cambiando los spinlocks de rxnet-\u0026gt;peer_hash_lock nuevamente a bloqueos que deshabilitan BH. ================================= ADVERTENCIA: estado de bloqueo inconsistente 6.13.0-rc5-build2+ #1223 Tainted: G E -------------------------------- inconsistent {SOFTIRQ-ON-W} -\u0026gt; {IN-SOFTIRQ-W} usage. swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes: ffff88810babe228 (\u0026amp;rxnet-\u0026gt;peer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180 {SOFTIRQ-ON-W} state was registered at: mark_usage+0x164/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_peer_keepalive_worker+0x144/0x440 process_one_work+0x486/0x7c0 process_scheduled_works+0x73/0x90 worker_thread+0x1c8/0x2a0 kthread+0x19b/0x1b0 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 irq event stamp: 972402 hardirqs last enabled at (972402): [] _raw_spin_unlock_irqrestore+0x2e/0x50 hardirqs last disabled at (972401): [] _raw_spin_lock_irqsave+0x18/0x60 softirqs last enabled at (972300): [] handle_softirqs+0x3ee/0x430 softirqs last disabled at (972313): [] __irq_exit_rcu+0x44/0x110 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(\u0026amp;rxnet-\u0026gt;peer_hash_lock);  lock(\u0026amp;rxnet-\u0026gt;peer_hash_lock); *** DEADLOCK *** 1 lock held by swapper/1/0: #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30 stack backtrace: CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G E 6.13.0-rc5-build2+ #1223 Tainted: [E]=UNSIGNED_MODULE Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace:  dump_stack_lvl+0x57/0x80 print_usage_bug.part.0+0x227/0x240 valid_state+0x53/0x70 mark_lock_irq+0xa5/0x2f0 mark_lock+0xf7/0x170 mark_usage+0xe1/0x180 __lock_acquire+0x544/0x990 lock_acquire.part.0+0x103/0x280 _raw_spin_lock+0x2f/0x40 rxrpc_put_peer+0xcb/0x180 afs_free_addrlist+0x46/0x90 [kafs] rcu_do_batch+0x2d2/0x640 rcu_core+0x2f7/0x350 handle_softirqs+0x1ee/0x430 __irq_exit_rcu+0x44/0x110 irq_exit_rcu+0xa/0x30 sysvec_apic_timer_interrupt+0x7f/0xa0  \"}],\"affected\":[{\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"affectedData\":[{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"unaffected\",\"programFiles\":[\"net/rxrpc/peer_event.c\",\"net/rxrpc/peer_object.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"72904d7b9bfbf2dd146254edea93958bc35bbbfe\",\"lessThan\":\"10ba5a3d57af20e494e0d979d1894260989235dd\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"72904d7b9bfbf2dd146254edea93958bc35bbbfe\",\"lessThan\":\"0e77dd41689637ac4e1b8fe0f27541f373640855\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"72904d7b9bfbf2dd146254edea93958bc35bbbfe\",\"lessThan\":\"79d458c13056559d49b5e41fbc4b6890e68cf65b\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"056fc740be000d39a7dba700a935f3bbfbc664e6\",\"versionType\":\"git\",\"status\":\"affected\"},{\"version\":\"6.7.3\",\"lessThan\":\"6.8\",\"versionType\":\"semver\",\"status\":\"affected\"}]},{\"vendor\":\"Linux\",\"product\":\"Linux\",\"defaultStatus\":\"affected\",\"programFiles\":[\"net/rxrpc/peer_event.c\",\"net/rxrpc/peer_object.c\"],\"repo\":\"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\"versions\":[{\"version\":\"6.8\",\"status\":\"affected\"},{\"version\":\"0\",\"lessThan\":\"6.8\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.12.13\",\"lessThanOrEqual\":\"6.12.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.13.2\",\"lessThanOrEqual\":\"6.13.*\",\"versionType\":\"semver\",\"status\":\"unaffected\"},{\"version\":\"6.14\",\"lessThanOrEqual\":\"*\",\"versionType\":\"original_commit_for_fix\",\"status\":\"unaffected\"}]}]}],\"metrics\":{\"cvssMetricV31\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6},{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"cvssData\":{\"version\":\"3.1\",\"vectorString\":\"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H\",\"baseScore\":5.5,\"baseSeverity\":\"MEDIUM\",\"attackVector\":\"LOCAL\",\"attackComplexity\":\"LOW\",\"privilegesRequired\":\"LOW\",\"userInteraction\":\"NONE\",\"scope\":\"UNCHANGED\",\"confidentialityImpact\":\"NONE\",\"integrityImpact\":\"NONE\",\"availabilityImpact\":\"HIGH\"},\"exploitabilityScore\":1.8,\"impactScore\":3.6}],\"ssvcV203\":[{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"ssvcData\":{\"timestamp\":\"2025-10-01T19:28:41.037357Z\",\"id\":\"CVE-2025-21809\",\"options\":[{\"exploitation\":\"none\"},{\"automatable\":\"no\"},{\"technicalImpact\":\"partial\"}],\"role\":\"CISA Coordinator\",\"version\":\"2.0.3\"}}]},\"weaknesses\":[{\"source\":\"nvd@nist.gov\",\"type\":\"Primary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-667\"}]},{\"source\":\"134c704f-9b21-4f2e-91b3-4a467353bcc0\",\"type\":\"Secondary\",\"description\":[{\"lang\":\"en\",\"value\":\"CWE-667\"}]}],\"configurations\":[{\"nodes\":[{\"operator\":\"OR\",\"negate\":false,\"cpeMatch\":[{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.7.3\",\"versionEndExcluding\":\"6.12.13\",\"matchCriteriaId\":\"3E9F5C4F-14D8-4DCE-A228-7F073932D0D0\"},{\"vulnerable\":true,\"criteria\":\"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\",\"versionStartIncluding\":\"6.13\",\"versionEndExcluding\":\"6.13.2\",\"matchCriteriaId\":\"6D4116B1-1BFD-4F23-BA84-169CC05FC5A3\"}]}]}],\"references\":[{\"url\":\"https://git.kernel.org/stable/c/0e77dd41689637ac4e1b8fe0f27541f373640855\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/10ba5a3d57af20e494e0d979d1894260989235dd\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]},{\"url\":\"https://git.kernel.org/stable/c/79d458c13056559d49b5e41fbc4b6890e68cf65b\",\"source\":\"416baaa9-dc9f-4396-8d5f-8c081fb06d67\",\"tags\":[\"Patch\"]}]}}",
    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-06-30T00:00:16+00:00",
      "cve": "CVE-2025-21809",
      "id": "CVE-2025-21809",
      "initial_release_date": "2025-02-27T00:00:00+00:00",
      "product_status:known_affected": "108",
      "product_status:known_not_affected": "166",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: rxrpc, afs: Fix peer hash locking vs RCU callback",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2025/cve-2025-21809.json",
      "version": "3"
    },
    "vulnrichment": {
      "containers": "{\"adp\": [{\"title\": \"CISA ADP Vulnrichment\", \"metrics\": [{\"cvssV3_1\": {\"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\"}}, {\"other\": {\"type\": \"ssvc\", \"content\": {\"id\": \"CVE-2025-21809\", \"role\": \"CISA Coordinator\", \"options\": [{\"Exploitation\": \"none\"}, {\"Automatable\": \"no\"}, {\"Technical Impact\": \"partial\"}], \"version\": \"2.0.3\", \"timestamp\": \"2025-10-01T19:28:41.037357Z\"}}}], \"problemTypes\": [{\"descriptions\": [{\"lang\": \"en\", \"type\": \"CWE\", \"cweId\": \"CWE-667\", \"description\": \"CWE-667 Improper Locking\"}]}], \"providerMetadata\": {\"orgId\": \"134c704f-9b21-4f2e-91b3-4a467353bcc0\", \"shortName\": \"CISA-ADP\", \"dateUpdated\": \"2025-10-01T16:56:48.437Z\"}}], \"cna\": {\"title\": \"rxrpc, afs: Fix peer hash locking vs RCU callback\", \"affected\": [{\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"72904d7b9bfbf2dd146254edea93958bc35bbbfe\", \"lessThan\": \"10ba5a3d57af20e494e0d979d1894260989235dd\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"72904d7b9bfbf2dd146254edea93958bc35bbbfe\", \"lessThan\": \"0e77dd41689637ac4e1b8fe0f27541f373640855\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"72904d7b9bfbf2dd146254edea93958bc35bbbfe\", \"lessThan\": \"79d458c13056559d49b5e41fbc4b6890e68cf65b\", \"versionType\": \"git\"}, {\"status\": \"affected\", \"version\": \"056fc740be000d39a7dba700a935f3bbfbc664e6\", \"versionType\": \"git\"}], \"programFiles\": [\"net/rxrpc/peer_event.c\", \"net/rxrpc/peer_object.c\"], \"defaultStatus\": \"unaffected\"}, {\"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\", \"vendor\": \"Linux\", \"product\": \"Linux\", \"versions\": [{\"status\": \"affected\", \"version\": \"6.8\"}, {\"status\": \"unaffected\", \"version\": \"0\", \"lessThan\": \"6.8\", \"versionType\": \"semver\"}, {\"status\": \"unaffected\", \"version\": \"6.12.13\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.12.*\"}, {\"status\": \"unaffected\", \"version\": \"6.13.2\", \"versionType\": \"semver\", \"lessThanOrEqual\": \"6.13.*\"}, {\"status\": \"unaffected\", \"version\": \"6.14\", \"versionType\": \"original_commit_for_fix\", \"lessThanOrEqual\": \"*\"}], \"programFiles\": [\"net/rxrpc/peer_event.c\", \"net/rxrpc/peer_object.c\"], \"defaultStatus\": \"affected\"}], \"references\": [{\"url\": \"https://git.kernel.org/stable/c/10ba5a3d57af20e494e0d979d1894260989235dd\"}, {\"url\": \"https://git.kernel.org/stable/c/0e77dd41689637ac4e1b8fe0f27541f373640855\"}, {\"url\": \"https://git.kernel.org/stable/c/79d458c13056559d49b5e41fbc4b6890e68cf65b\"}], \"x_generator\": {\"engine\": \"bippy-1.2.0\"}, \"descriptions\": [{\"lang\": \"en\", \"value\": \"In the Linux kernel, the following vulnerability has been resolved:\\n\\nrxrpc, afs: Fix peer hash locking vs RCU callback\\n\\nIn its address list, afs now retains pointers to and refs on one or more\\nrxrpc_peer objects.  The address list is freed under RCU and at this time,\\nit puts the refs on those peers.\\n\\nNow, when an rxrpc_peer object runs out of refs, it gets removed from the\\npeer hash table and, for that, rxrpc has to take a spinlock.  However, it\\nis now being called from afs\u0027s RCU cleanup, which takes place in BH\\ncontext - but it is just taking an ordinary spinlock.\\n\\nThe put may also be called from non-BH context, and so there exists the\\npossibility of deadlock if the BH-based RCU cleanup happens whilst the hash\\nspinlock is held.  This led to the attached lockdep complaint.\\n\\nFix this by changing spinlocks of rxnet-\u003epeer_hash_lock back to\\nBH-disabling locks.\\n\\n    ================================\\n    WARNING: inconsistent lock state\\n    6.13.0-rc5-build2+ #1223 Tainted: G            E\\n    --------------------------------\\n    inconsistent {SOFTIRQ-ON-W} -\u003e {IN-SOFTIRQ-W} usage.\\n    swapper/1/0 [HC0[0]:SC1[1]:HE1:SE0] takes:\\n    ffff88810babe228 (\u0026rxnet-\u003epeer_hash_lock){+.?.}-{3:3}, at: rxrpc_put_peer+0xcb/0x180\\n    {SOFTIRQ-ON-W} state was registered at:\\n      mark_usage+0x164/0x180\\n      __lock_acquire+0x544/0x990\\n      lock_acquire.part.0+0x103/0x280\\n      _raw_spin_lock+0x2f/0x40\\n      rxrpc_peer_keepalive_worker+0x144/0x440\\n      process_one_work+0x486/0x7c0\\n      process_scheduled_works+0x73/0x90\\n      worker_thread+0x1c8/0x2a0\\n      kthread+0x19b/0x1b0\\n      ret_from_fork+0x24/0x40\\n      ret_from_fork_asm+0x1a/0x30\\n    irq event stamp: 972402\\n    hardirqs last  enabled at (972402): [\u003cffffffff8244360e\u003e] _raw_spin_unlock_irqrestore+0x2e/0x50\\n    hardirqs last disabled at (972401): [\u003cffffffff82443328\u003e] _raw_spin_lock_irqsave+0x18/0x60\\n    softirqs last  enabled at (972300): [\u003cffffffff810ffbbe\u003e] handle_softirqs+0x3ee/0x430\\n    softirqs last disabled at (972313): [\u003cffffffff810ffc54\u003e] __irq_exit_rcu+0x44/0x110\\n\\n    other info that might help us debug this:\\n     Possible unsafe locking scenario:\\n           CPU0\\n           ----\\n      lock(\u0026rxnet-\u003epeer_hash_lock);\\n      \u003cInterrupt\u003e\\n        lock(\u0026rxnet-\u003epeer_hash_lock);\\n\\n     *** DEADLOCK ***\\n    1 lock held by swapper/1/0:\\n     #0: ffffffff83576be0 (rcu_callback){....}-{0:0}, at: rcu_lock_acquire+0x7/0x30\\n\\n    stack backtrace:\\n    CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G            E      6.13.0-rc5-build2+ #1223\\n    Tainted: [E]=UNSIGNED_MODULE\\n    Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014\\n    Call Trace:\\n     \u003cIRQ\u003e\\n     dump_stack_lvl+0x57/0x80\\n     print_usage_bug.part.0+0x227/0x240\\n     valid_state+0x53/0x70\\n     mark_lock_irq+0xa5/0x2f0\\n     mark_lock+0xf7/0x170\\n     mark_usage+0xe1/0x180\\n     __lock_acquire+0x544/0x990\\n     lock_acquire.part.0+0x103/0x280\\n     _raw_spin_lock+0x2f/0x40\\n     rxrpc_put_peer+0xcb/0x180\\n     afs_free_addrlist+0x46/0x90 [kafs]\\n     rcu_do_batch+0x2d2/0x640\\n     rcu_core+0x2f7/0x350\\n     handle_softirqs+0x1ee/0x430\\n     __irq_exit_rcu+0x44/0x110\\n     irq_exit_rcu+0xa/0x30\\n     sysvec_apic_timer_interrupt+0x7f/0xa0\\n     \u003c/IRQ\u003e\"}], \"cpeApplicability\": [{\"nodes\": [{\"negate\": false, \"cpeMatch\": [{\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.12.13\", \"versionStartIncluding\": \"6.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.13.2\", \"versionStartIncluding\": \"6.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionEndExcluding\": \"6.14\", \"versionStartIncluding\": \"6.8\"}, {\"criteria\": \"cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*\", \"vulnerable\": true, \"versionStartIncluding\": \"6.7.3\"}], \"operator\": \"OR\"}]}], \"providerMetadata\": {\"orgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"shortName\": \"Linux\", \"dateUpdated\": \"2026-05-11T21:06:57.130Z\"}}}",
      "cveMetadata": "{\"cveId\": \"CVE-2025-21809\", \"state\": \"PUBLISHED\", \"dateUpdated\": \"2026-05-11T21:06:57.130Z\", \"dateReserved\": \"2024-12-29T08:45:45.772Z\", \"assignerOrgId\": \"416baaa9-dc9f-4396-8d5f-8c081fb06d67\", \"datePublished\": \"2025-02-27T20:01:00.969Z\", \"assignerShortName\": \"Linux\"}",
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



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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.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • 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.