Linux Kernel up to 7.3-rc1 lockdep kernel/locking/lockdep.c hlock_class class_idx

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9.5	$0-$5k	0.00-

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.3-rc1. It has been rated as very critical. Impacted is the function hlock_class of the file kernel/locking/lockdep.c of the component lockdep. Performing a manipulation of the argument class_idx results in locking. This vulnerability was named CVE-2026-98398. The attack may be initiated remotely. There is no available exploit. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 7.3-rc1. This affects the function hlock_class of the file kernel/locking/lockdep.c of the component lockdep. The manipulation of the argument class_idx with an unknown input leads to a locking vulnerability. CWE is classifying the issue as CWE-667. The product does not properly acquire or release a lock on a resource, leading to unexpected resource state changes and behaviors. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: locking/lockdep: Invalidate stale class_cache entries for zapped classes syzbot reported a lockdep splat hitting DEBUG_LOCKS_WARN_ON(1) in hlock_class() due to an invalid class_idx: WARNING: kernel/locking/lockdep.c:238 at __lock_acquire+0x382/0x2cf0 kernel/locking/lockdep.c:5203 Workqueue: wg-crypt-wg0 wg_packet_tx_worker RIP: 0010:hlock_class kernel/locking/lockdep.c:238 [inline] RIP: 0010:check_wait_context kernel/locking/lockdep.c:4870 [inline] RIP: 0010:__lock_acquire+0x389/0x2cf0 kernel/locking/lockdep.c:5203 Call Trace: <IRQ> lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886 _raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:173 tcp_tsq_handler+0x29/0x200 net/ipv4/tcp_output.c:1291 tcp_tsq_workfn+0x384/0x410 net/ipv4/tcp_output.c:1325 ... When a lock class is zapped (e.g. during module unload or key unregistration), zap_class() clears the class's bit in lock_classes_in_use and removes it from the class hash table. However, existing lockdep_map instances embedded in data structures may still retain a pointer to the zapped class in their class_cache[] array. When __lock_acquire() subsequently runs on such a lock, it finds lock->class_cache[subclass] != NULL, skipping register_lock_class() and assigning hlock->class_idx to the index of the zapped class. When check_wait_context() or hlock_class() inspects the held_lock, it finds !test_bit(class_idx, lock_classes_in_use) and warns. Furthermore, if the zapped slot is subsequently re-allocated to an unrelated lock key, the stale class_cache entry would erroneously match the unrelated class (ABA issue). Add lock_class_cache_is_valid() to validate that the cached class is within lock_classes bounds, still allocated in lock_classes_in_use (using uninstrumented arch_test_bit() in __always_inline context so it is safe in noinstr contexts like match_held_lock()), and that class->key matches the expected subkey (taking lockdep_set_subclass() overrides into account). Also use READ_ONCE()/WRITE_ONCE() when accessing class_cache[]. If the entry is invalid or stale, fall back to register_lock_class() / look_up_lock_class().

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-98398 since 09/25/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 10/14/2026).

Upgrading to version 5.15.222, 6.1.189, 6.6.158, 6.12.111, 6.18.53, 7.2.7 or 7.3-rc2 eliminates this vulnerability. Applying the patch f8a1281ab82df5b51fd0384354d4b21daf2b7af0/1c9d664e2e067fca69e5a41d68e23bbc66a583fe/6bc345f6d81ebe22e0f355c2a21d7e29691f9332/f63c86e9d267629758adaba18579e784ddd63c32/c7acfb04c7e2e2dea248282b21373d93296644dd/baa320fbb2f9fea50f5632a307da8ce84fbef5bd is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.15.221
• 6.1.188
• 6.6.157
• 6.12.110
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
• 6.18.9
• 6.18.10
• 6.18.11
• 6.18.12
• 6.18.13
• 6.18.14
• 6.18.15
• 6.18.16
• 6.18.17
• 6.18.18
• 6.18.19
• 6.18.20
• 6.18.21
• 6.18.22
• 6.18.23
• 6.18.24
• 6.18.25
• 6.18.26
• 6.18.27
• 6.18.28
• 6.18.29
• 6.18.30
• 6.18.31
• 6.18.32
• 6.18.33
• 6.18.34
• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 6.18.40
• 6.18.41
• 6.18.42
• 6.18.43
• 6.18.44
• 6.18.45
• 6.18.46
• 6.18.47
• 6.18.48
• 6.18.49
• 6.18.50
• 6.18.51
• 6.18.52
• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5
• 7.2.6
• 7.3-rc1

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Locking
CWE: CWE-667
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.222/6.1.189/6.6.158/6.12.111/6.18.53/7.2.7/7.3-rc2
Patch: f8a1281ab82df5b51fd0384354d4b21daf2b7af0/1c9d664e2e067fca69e5a41d68e23bbc66a583fe/6bc345f6d81ebe22e0f355c2a21d7e29691f9332/f63c86e9d267629758adaba18579e784ddd63c32/c7acfb04c7e2e2dea248282b21373d93296644dd/baa320fbb2f9fea50f5632a307da8ce84fbef5bd

Timelineinfo

09/25/2026 CVE reserved
10/14/2026 +19 days Advisory disclosed
10/14/2026 +0 days VulDB entry created
10/14/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-98398 (🔒)
GCVE (CVE): GCVE-0-2026-98398
GCVE (VulDB): GCVE-100-419853

Entryinfo

Created: 10/14/2026 16:00
Changes: 10/14/2026 16:00 (61)
Complete: 🔍
Cache ID: 216::103

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Discussion

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