7.8

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

Modified
AliasesUBUNTU-CVE-2025-21851DEBIAN-CVE-2025-21851
Published 12-03-2025Last modified 05-08-2026

Vulnerability summary

CVE-2025-21851 is a high (CVSS 7.8) Improper Locking vulnerability in linux. EPSS estimates a 0.18% chance of exploitation in the next 30 days, higher than 7.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 7.8, local access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
7.8/10
010
High · v3.1 (CVE.org)
EPSS score
0.18%
0%100%
Low · 0.00 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 4 · Related 3
RHSA-2025:20095RHSA-2025:20518USN-7521-1USN-7521-3USN-7521-2

Timeline

  1. 12-03-2025
    PublishedVulnerability first disclosed.
  2. 05-08-2026
    Last modifiedVulnerability information updated.

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.

CVSS metrics

4 scores · 4 sources · 1 version

EPSS trend

Probability

0.18%

Chance of exploitation in the next 30 days

Percentile

7%

Versus all other CVEs

30-day change

No change 0.00 pp

From 0.17% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.

Ubuntu83 products
  • linux-allwinner-5.19All versions (No fix recorded)
  • linux-aws-5.0All versions (No fix recorded)
  • linux-aws-5.11All versions (No fix recorded)
  • linux-aws-5.13All versions (No fix recorded)
  • linux-aws-5.19All versions (No fix recorded)
Linux2 products
  • linux≥ 317460317a02a1af512697e6e964298dedd8a163, < c1f3f3892d4526f18aaeffdb6068ce861e793ee3 | ≥ 317460317a02a1af512697e6e964298dedd8a163, < 787d556a3de447e70964a4bdeba9196f62a62b1e | ≥ 317460317a02a1af512697e6e964298dedd8a163, < 517e8a7835e8cfb398a0aeb0133de50e31cae32b | 6.9
  • linux_kernelEOL≥ 6.9, < 6.12.17 | ≥ 6.13, < 6.13.5 | 6.9 | 6.14:rc1 | 6.14:rc2 | 6.14:rc3
Debian1 product
  • linux< 6.12.17-1

3 vendors · 86 products

References

10 links