CVE-2025-21815: mm/compaction: fix UBSAN shift-out-of-bounds warning
Vulnerability summary
CVE-2025-21815 is a high (CVSS 7.1) Out-of-bounds Read vulnerability in linux. EPSS estimates a 0.19% chance of exploitation in the next 30 days, higher than 9% of scored vulnerabilities.
Not severe (CVSS 7.1, local access); no exploitation reported by the 5 checked sources
Source freshness unavailable
How is this decided?Advisory lineage
Upstream 0 · Downstream 20 · Related 20Timeline
- 27-02-2025PublishedVulnerability first disclosed.
- 11-05-2026Last modifiedVulnerability information updated.
Description
In the Linux kernel, the following vulnerability has been resolved: mm/compaction: fix UBSAN shift-out-of-bounds warning syzkaller reported a UBSAN shift-out-of-bounds warning of (1UL << order) in isolate_freepages_block(). The bogus compound_order can be any value because it is union with flags. Add back the MAX_PAGE_ORDER check to fix the warning.
CVSS metrics
3 scores · 3 sources · 1 version- OSV · UbuntuEcosystem advisory · calculated7.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
- OSV · DebianEcosystem advisory · calculated7.1HighCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H
EPSS trend
Probability
0.19%
Chance of exploitation in the next 30 days
Percentile
9%
Versus all other CVEs
30-day change
No change 0.00 pp
From 0.19% on 04-10-2026
Known exploited
Compare KEV catalogs
CISA KEVNot in the CISA KEV catalog.
ENISA CNWNot in the ENISA CNW catalog.
CIRCLNot in the CIRCL catalog.
Public exploits
0 foundNo public exploits indexed.
Weaknesses
CWE · root causeAffected systems
Known conditions: local access, low-privilege account, no user interaction (CVSS vector). Other conditions: not stated in public data.
Ubuntu106 products
- linux< 6.8.0-64.67
- linux-allwinner-5.19All versions (No fix recorded)
- linux-aws< 6.8.0-1032.34
- linux-aws-5.0All versions (No fix recorded)
- linux-aws-5.11All versions (No fix recorded)
Linux2 products
- linux≥ 3da0272a4c7d0d37b47b28e87014f421296fc2be, < 4491159774d973a9e2e998d25d8fbb20fada6dfa | ≥ 3da0272a4c7d0d37b47b28e87014f421296fc2be, < 10b7d3eb535098ccd4c82a182a33655d8a0e5c88 | ≥ 3da0272a4c7d0d37b47b28e87014f421296fc2be, < d1366e74342e75555af2648a2964deb2d5c92200 | 6.7
- linux_kernel≥ 6.7, < 6.12.14 | ≥ 6.13, < 6.13.3
Debian1 product
- linux< 6.12.15-1
3 vendors · 109 products
