CVE-2026-90203Hinoki check available

Kernel memory disclosure or crash via negative offset

Published Sep 17, 2026 · Updated Sep 18, 2026

Out-of-bounds read in Linux allows local users to expose kernel memory or crash the host through a crafted Squashfs file. squashfs_copy_data() accepts a negative fragment offset from on-disk metadata and indexes before the fragment-cache pointer array before copying up to a page into a file folio. A privileged user must first mount the crafted filesystem with CAP_SYS_ADMIN; afterward, an unprivileged read of the crafted file triggers the disclosure or kernel crash.

CVSS severity7.1
High
EPSS probability0.17%
Next 30 days · Oct 19, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Out-of-bounds read in Linux allows local users to expose kernel memory or crash the host through a crafted Squashfs file. squashfs_copy_data() accepts a negative fragment offset from on-disk metadata and indexes before the fragment-cache pointer array before copying up to a page into a file folio. A privileged user must first mount the crafted filesystem with CAP_SYS_ADMIN; afterward, an unprivileged read of the crafted file triggers the disclosure or kernel crash.

The record

CVE
CVE-2026-90203
Published
Sep 17, 2026
Updated
Sep 18, 2026
Vendor
The Linux Kernel Organization
Product
Linux
Classifications
T1203
Attack vector
local
Privileges
unauthenticated

Timeline

How it unfolded

  1. Sep 17, 2026CVE publishedPublication date reported by the CVE source.
  2. Sep 18, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

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

  1. Affected versionversion=2.6.29
  2. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <3d2f0cb66c909ea2312cdef465165bb9a3ba2d84
  3. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <95dadf366c117dcdca78a570e6832071deab1ecd
  4. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <b169185d5c672b989985c6c2e38cafab2548ba88
  5. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <bbb2218eb072b0a15dc063929200183bd23c2344
  6. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <c2a126fca820ae74872da28de68dc74d4595dc4b
  7. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <d0a3729d464fcf516416a41cf304c0c92126ee03
  8. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <e300eb5002925b29be803d2661af07266cfa267e
  9. Affected versionversion=f400e12656ab518be107febfe2315fb1eab5a342 <e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe

What conditions does exploitation require?

Attack vectorlocal
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linuxversion=2.6.29; version=f400e12656ab518be107febfe2315fb1eab5a342 <3d2f0cb66c909ea2312cdef465165bb9a3ba2d84; version=f400e12656ab518be107febfe2315fb1eab5a342 <95dadf366c117dcdca78a570e6832071deab1ecd; version=f400e12656ab518be107febfe2315fb1eab5a342 <b169185d5c672b989985c6c2e38cafab2548ba88; version=f400e12656ab518be107febfe2315fb1eab5a342 <bbb2218eb072b0a15dc063929200183bd23c2344; version=f400e12656ab518be107febfe2315fb1eab5a342 <c2a126fca820ae74872da28de68dc74d4595dc4b; version=f400e12656ab518be107febfe2315fb1eab5a342 <d0a3729d464fcf516416a41cf304c0c92126ee03; version=f400e12656ab518be107febfe2315fb1eab5a342 <e300eb5002925b29be803d2661af07266cfa267e; version=f400e12656ab518be107febfe2315fb1eab5a342 <e4afd90bc7bf3dd477970c6c42bdd29ad3fda7fe

Published CVSS scores

7.1Linux CNACVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:N/A:H
5.1Amazon LinuxCVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:L/I:N/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.

Activity data is delayed. The latest report is Sep 28, 2026.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 22, 2026Sep 28, 2026
Latest reporting daySep 28, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1203Exploitation for Client Execution

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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