CVE-2025-21785

Boot-time memory corruption via cache-leaf miscount

Published Feb 27, 2025 · Updated Aug 5, 2026

An out-of-bounds write in Linux arm64 cacheinfo handling corrupts kernel memory during boot on systems with inconsistent cache descriptions. The cacheinfo population loop advances its array index once per cache level, even when separate instruction and data leaves consume two entries. Reachability requires pre-existing inconsistencies between firmware cache tables and hardware registers; Ubuntu states that these are not attacker-controllable.

CVSS severity7.8
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

An out-of-bounds write in Linux arm64 cacheinfo handling corrupts kernel memory during boot on systems with inconsistent cache descriptions. The cacheinfo population loop advances its array index once per cache level, even when separate instruction and data leaves consume two entries. Reachability requires pre-existing inconsistencies between firmware cache tables and hardware registers; Ubuntu states that these are not attacker-controllable.

The record

CVE
CVE-2025-21785
Published
Feb 27, 2025
Updated
Aug 5, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
CWE-787
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 27, 2025CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=4.0
  2. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <4371ac7b494e933fffee2bd6265d18d73c4f05aa
  3. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <4ff25f0b18d1d0174c105e4620428bcdc1213860
  4. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <67b99a2b5811df4294c2ad50f9bff3b6a08bd618
  5. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <715eb1af64779e1b1aa0a7b2ffb81414d9f708e5
  6. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <875d742cf5327c93cba1f11e12b08d3cce7a88d2
  7. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <88a3e6afaf002250220793df99404977d343db14
  8. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <ab90894f33c15b14c1cee6959ab6c8dcb09127f8
  9. Affected versionversion=5d425c18653731af62831d30a4fa023d532657a9 <e4fde33107351ec33f1a64188612fbc6ca659284

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=4.0; version=5d425c18653731af62831d30a4fa023d532657a9 <4371ac7b494e933fffee2bd6265d18d73c4f05aa; version=5d425c18653731af62831d30a4fa023d532657a9 <4ff25f0b18d1d0174c105e4620428bcdc1213860; version=5d425c18653731af62831d30a4fa023d532657a9 <67b99a2b5811df4294c2ad50f9bff3b6a08bd618; version=5d425c18653731af62831d30a4fa023d532657a9 <715eb1af64779e1b1aa0a7b2ffb81414d9f708e5; version=5d425c18653731af62831d30a4fa023d532657a9 <875d742cf5327c93cba1f11e12b08d3cce7a88d2; version=5d425c18653731af62831d30a4fa023d532657a9 <88a3e6afaf002250220793df99404977d343db14; version=5d425c18653731af62831d30a4fa023d532657a9 <ab90894f33c15b14c1cee6959ab6c8dcb09127f8; version=5d425c18653731af62831d30a4fa023d532657a9 <e4fde33107351ec33f1a64188612fbc6ca659284

Published CVSS scores

7.8kernel.orgCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-787Out-of-bounds Write

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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