CVE-2026-45837bpf: Fix use-after-free in arena_vm_close on fork
- 7.8HighCVSS base score
- 0.12%Exploitation in 30 daysEPSS · top 98% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By Linux
- 14 days later
· 14 days later
Published
- 18 days later
· 18 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| NVDNVD · Analyzed | 3.1 | High7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.12% · top 98% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.8.
Affected products
- affected 317460317a02a1af512697e6e964298dedd8a163 – < 723b9fa930cc277c15ce6b9ec9feec828cfac9d7
- affected 317460317a02a1af512697e6e964298dedd8a163 – < d18099f19e53250f8ad2801498b88cec29d9107a
- affected 317460317a02a1af512697e6e964298dedd8a163 – < 201128fcc7b213d27ab77bc4e89488b41796480f
- affected 317460317a02a1af512697e6e964298dedd8a163 – < 4fddde2a732de60bb97e3307d4eb69ac5f1d2b74
- affected 6.9
- unaffected < 6.9
- unaffected 6.12.88 – ≤ 6.12.*
- unaffected 6.18.30 – ≤ 6.18.*
- unaffected 7.0.7 – ≤ 7.0.*
- unaffected 7.1 – ≤ *
References
References4
- https://git.kernel.org/stable/c/723b9fa930cc277c15ce6b9ec9feec828cfac9d7 (opens in a new tab)
- https://git.kernel.org/stable/c/d18099f19e53250f8ad2801498b88cec29d9107a (opens in a new tab)
- https://git.kernel.org/stable/c/201128fcc7b213d27ab77bc4e89488b41796480f (opens in a new tab)
- https://git.kernel.org/stable/c/4fddde2a732de60bb97e3307d4eb69ac5f1d2b74 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-32163 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-45837)Record last updated .