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CVE-2026-98537

Linux: workqueue: Fix NULL current_pwq deref in flush dependency check

Linux LinuxOperating systems
Open in ThreatlineRecord JSON
CVSS
NoneNot scored
ExploitationNo known exploitationNot in CISA KEV, which does not prove it is unexploitedCISA KEV
Exploit odds (EPSS)0.22%Chance of exploitation activity in the next 30 days, higher than 11% of CVEs. Scored 23 Oct 2026FIRST EPSS
Fixed in8ffececcb88262389b4f91fed0fe4884b68204bcAlso 9bb739a5c5a570c28a62afb98e9326e2a49743c1, 513121e69388604619ea8c0ee07e86a3d1b5b5dc and 2 moreCVE List
Published18 Oct 2026Updated 19 Oct 2026CVE List

What fixes it

  • 8ffececcb88262389b4f91fed0fe4884b68204bcLinuxCVE List
  • 9bb739a5c5a570c28a62afb98e9326e2a49743c1LinuxCVE List
  • 513121e69388604619ea8c0ee07e86a3d1b5b5dcLinuxCVE List
  • 0c6b9b1e295aeff1132ac7aa738148cc65f06485LinuxCVE List
  • 1dccf5dc2f8fe688270b261ca4216e03c6a1e674LinuxCVE List

A fixed version on one release line is not the upgrade target for every line. Check your exact version and any vendor backports.

Description

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

workqueue: Fix NULL current_pwq deref in flush dependency check

check_flush_dependency() uses current_wq_worker() to determine whether the caller is a workqueue worker and then dereferences worker->current_pwq to test whether the current workqueue is WQ_MEM_RECLAIM.

current_wq_worker() only means that %current has PF_WQ_WORKER set. A kworker can reach check_flush_dependency() while it is not executing a work item. One such path is worker_thread() acting as the pool manager, where create_worker() does GFP_KERNEL allocation and the allocation path invokes the OOM notifier. In that state worker->current_pwq is NULL because current_pwq is set only by process_one_work() and cleared again after the work function returns.

[ 416.760634][ T375] Call trace: [ 416.760638][ T375] check_flush_dependency+0x80/0x120 (P) [ 416.760648][ T375] __flush_work+0x98/0x224 [ 416.760657][ T375] flush_work+0x30/0x44 [ 416.760665][ T375] ... [ 416.760710][ T375] blocking_notifier_call_chain+0x58/0xa0 [ 416.760719][ T375] out_of_memory+0xb4/0x458 [ 416.760730][ T375] __alloc_pages_may_oom+0x11c/0x1a8 [ 416.760739][ T375] __alloc_pages_slowpath+0x314/0x46c [ 416.760746][ T375] __alloc_frozen_pages_noprof+0x110/0x1a4 [ 416.760753][ T375] new_slab+0x12c/0x484 [ 416.760759][ T375] ___slab_alloc+0x7a8/0xc7c [ 416.760765][ T375] __slab_alloc+0x74/0xd8 [ 416.760772][ T375] __kmalloc_cache_node_noprof+0x2ac/0x304 [ 416.760779][ T375] alloc_worker+0x28/0x60 [ 416.760785][ T375] create_worker+0x4c/0x20c [ 416.760790][ T375] worker_thread+0xe8/0x2b8 [ 416.760796][ T375] kthread+0x1a8/0x200 [ 416.760805][ T375] ret_from_fork+0x10/0x20

Guard the WQ_MEM_RECLAIM-worker warning with worker->current_pwq. If the kworker is not currently executing a work item, there is no current workqueue to diagnose with that warning. The PF_MEMALLOC warning is left unchanged so explicit reclaim context flushing a !WQ_MEM_RECLAIM target is still reported.

Text from CVE List

Affected versions 18

  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before 8ffececcb88262389b4f91fed0fe4884b68204bcCVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before 9bb739a5c5a570c28a62afb98e9326e2a49743c1CVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before cc190a6a1d20b87e6a9435202fc2a3bd84c79fb3CVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before 513121e69388604619ea8c0ee07e86a3d1b5b5dcCVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before 0c6b9b1e295aeff1132ac7aa738148cc65f06485CVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before 1dccf5dc2f8fe688270b261ca4216e03c6a1e674CVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before f97e6d0572d1b39998e053732332bc3cfdd0b9aaCVE List
  • Linuxaffected: fca839c00a12d682cb59b3b620d109a1d850b262 before db6365ced4d5855e321f772b240c0e473bcfcdd5CVE List
  • Linuxaffected: 4.5CVE List
  • Linuxunaffected: all versions before 4.5CVE List
  • Linuxunaffected: 5.10.271 through 5.10.*CVE List
  • Linuxunaffected: 5.15.222 through 5.15.*CVE List
  • Linuxunaffected: 6.1.189 through 6.1.*CVE List
  • Linuxunaffected: 6.6.158 through 6.6.*CVE List
  • Linuxunaffected: 6.12.112 through 6.12.*CVE List
  • Linuxunaffected: 6.18.55 through 6.18.*CVE List
  • Linuxunaffected: 7.2.9 through 7.2.*CVE List
  • Linuxunaffected: 7.3CVE List

References 8