CVE-2026-45837

High

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix use-after-free in arena_vm_close on fork arena_vm_open() only bumps vml->mmap_count but never registers the child VMA in arena->vma_list. The vml->vma always points at the parent VMA, so after parent munmap the pointer dangles. If the child then calls bpf_arena_free_pages(), zap_pages() reads the stale vml->vma triggering use-after-free. Fix this by preventing the arena VMA from being inherited across fork with VM_DONTCOPY, and preventing VMA splits via the may_split callback. Also reject mremap with a .mremap callback returning -EINVAL. A same-size mremap(MREMAP_FIXED) on the full arena VMA reaches copy_vma() through the following path: check_prep_vma() - returns 0 early: new_len == old_len skips VM_DONTEXPAND check prep_move_vma() - vm_start == old_addr and vm_end == old_addr + old_len so may_split is never called move_vma() copy_vma_and_data() copy_vma() vm_area_dup() - copies vm_private_data (vml pointer) vm_ops->open() - bumps vml->mmap_count vm_ops->mremap() - returns -EINVAL, rollback unmaps new VMA The refcount ensures the rollback's arena_vm_close does not free the vml shared with the original VMA.

Package Linux Kernel
Published 2026-05-27
Last modified 2026-06-26
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

7.8

out of 10
High
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Weakness type

CWE-416

CVE-2026-45837 is a Use After Free vulnerability

What is Use After Free?

The product references memory after it has been freed, which may cause it to crash, use unexpected values, or execute code. Learn more on MITRE CWE

Affected versions

Linux kernel versions 6.9 and later are affected. Fixed in 6.12.88, 6.18.30, 7.0.7, 7.1 and their respective stable series.

Affected from
≥ 6.9
Fixed in
✓ 6.12.88 6.12.x ✓ 6.18.30 6.18.x ✓ 7.0.7 7.0.x ✓ 7.1

References

4 total

Frequently asked questions

  • What is CVE-2026-45837?

    CVE-2026-45837 is a High severity Linux kernel vulnerability with a CVSS score of 7.8 out of 10 , classified as an Use After Free flaw (CWE-416) . It affects Linux kernel versions from 6.9 onward and has been patched in 6.12.88, 6.18.30, 7.0.7 and others. CVE-2026-45837 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-45837?

    CVE-2026-45837 has a CVSS score of 7.8 out of 10, rated High severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H .

  • Is there a patch available for CVE-2026-45837?

    Yes. CVE-2026-45837 has been patched. Fixed versions include 6.12.88, 6.18.30, 7.0.7 and others. If you are running Linux kernel 6.9 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-45837 actively exploited?

    No. CVE-2026-45837 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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