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Back to active CVEs
High · CVSS 7.8CVE-2025-21851

bpf: Fix softlockup in arena_map_free on 64k page kernelCVE-2025-21851

Answer in brief

CVE-2025-21851 records a High severity (CVSS 7.8) vulnerability in bpf: Fix softlockup in arena_map_free on 64k page kernel. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Analysis pending evidence review

HOL Guard separates source facts from reviewed analysis. See the methodology.

Published Mar 12, 2025Updated Aug 5, 2026Source checked Nov 4, 2026First seen by HOL Aug 5, 2026Material review Aug 5, 2026
Upstream Advisory

Key facts

Risk
High · CVSS 7.8
Exploitation
Not marked as known exploited
Affected software
2 mapped packages or products
Fix availability
Available

Why this deserves its current priority

CVSS is 7.8. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.

Analysis status

Analysis pending evidence review

Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.

Affected scope and exposure questions

The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.

Mapped affected packages and fixed versions
PackageAffected rangeFixed version
Linux/Linuxgeneric6.9Not reported
Linux/Linuxgeneric>=317460317a02a1af512697e6e964298dedd8a163 <c1f3f3892d4526f18aaeffdb6068ce861e793ee3 || >=317460317a02a1af512697e6e964298dedd8a163 <787d556a3de447e70964a4bdeba9196f62a62b1e || >=317460317a02a1af512697e6e964298dedd8a163 <517e8a7835e8cfb398a0aeb0133de50e31cae32bc1f3f3892d4526f18aaeffdb6068ce861e793ee3, 787d556a3de447e70964a4bdeba9196f62a62b1e, 517e8a7835e8cfb398a0aeb0133de50e31cae32b

Recommended response

  1. 1Check inventory. Check lockfiles and deployed manifests for Linux/Linux, Linux/Linux.
  2. 2Review the reported fix. Update Linux/Linux to c1f3f3892d4526f18aaeffdb6068ce861e793ee3 if you use the affected versions. Test the change in a non-production environment first.

Evidence timeline and material changes

  1. Published upstream

    Mar 12, 2025

    Evidence: source:cvelist:source_dates:source-dates:record

  2. Source modified

    Aug 5, 2026

    Evidence: source:cvelist:source_dates:source-dates:record

  3. First seen by HOL

    Aug 5, 2026

Sources and claim methodology

  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
  • Source referencegit.kernel.org
Upstream source description

In the Linux kernel, the following vulnerability has been resolved: bpf: Fix softlockup in arena_map_free on 64k page kernel On an aarch64 kernel with CONFIG_PAGE_SIZE_64KB=y, arena_htab tests cause a segmentation fault and soft lockup. The same failure is not observed with 4k pages on aarch64. It turns out arena_map_free() is calling apply_to_existing_page_range() with the address returned by bpf_arena_get_kern_vm_start(). If this address is not page-aligned the code ends up calling apply_to_pte_range() with that unaligned address causing soft lockup. Fix it by round up GUARD_SZ to PAGE_SIZE << 1 so that the division by 2 in bpf_arena_get_kern_vm_start() returns a page-aligned value.

Quoted source text, attributed separately from HOL analysis.

Record context

Vulnerability class
Vulnerability
EPSS
Not reported
CWE IDs
CWE-667
Source
CVE List V5
Source checked
Nov 4, 2026
References
3 linked sources
Open source record