CVE-2026-98636 - Vulnerability Details

- squashfs: Add dictionary size range check to prevent shift-out-of-bounds

Description

In the Linux kernel, the following vulnerability has been resolved:

squashfs: Add dictionary size range check to prevent shift-out-of-bounds

When an abnormal SquashFS image (COMP_OPTS flag is 1 but dictionary size
is 0) is mounted, and performs shift operations using dictionarysize, the
shift exponent is -1, causing a shift-out-of-bounds.

Detail as below:
squashfs_comp_opts(msblk, buffer, length)
squashfs_xz_comp_opts()
if (comp_opts)
n = ffs(opts->dict_size) - 1;<----opts->dict_size=0, n=-1
if (opts->dict_size != (1 << n) && opts->dict_size !=
(1 << n) + (1 << (n + 1))) <----shift-out-of-bounds

Fix it by adding a dictionary size range check before the shift operation.

Published: 2026-10-18

Score: 4.4 Medium

EPSS: < 1% Very Low

KEV: No

Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).

Vendor Product Default status Versions

Linux

unaffected

Version	Status	Constraints
`ff750311d30acc9564ef577050794953eee59f01`	affected	< b02948a23455f8190a53887b2d2c13ae1d360cea
`ff750311d30acc9564ef577050794953eee59f01`	affected	< 9d9c5c218ea356a1d88765214ad2919605280ab1
`ff750311d30acc9564ef577050794953eee59f01`	affected	< 7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1
`ff750311d30acc9564ef577050794953eee59f01`	affected	< c68e0068a236f9a7dfc19720bdf11e5d80a85089
`ff750311d30acc9564ef577050794953eee59f01`	affected	< 88c673a0bd233df44ca0020da82f4fd3876de27a
`ff750311d30acc9564ef577050794953eee59f01`	affected	< 0cb85377daaefb4ce5ce72975f2deb27ee0e0cad
`ff750311d30acc9564ef577050794953eee59f01`	affected	< e1ca4e3a380ef3e8f46ce006f1146392e3f32c98
`ff750311d30acc9564ef577050794953eee59f01`	affected	< 1f7745fb3580152ca902ef181b605f33cabfb1d0

Linux

affected

Version	Status	Constraints
`2.6.39`	affected	—
`0`	unaffected	< 2.6.39
`5.10.271`	unaffected	≤ 5.10.*
`5.15.222`	unaffected	≤ 5.15.*
`6.1.189`	unaffected	≤ 6.1.*
`6.6.158`	unaffected	≤ 6.6.*
`6.12.112`	unaffected	≤ 6.12.*
`6.18.55`	unaffected	≤ 6.18.*
`7.2.9`	unaffected	≤ 7.2.*
`7.3`	unaffected	≤ *

No data.

Vendor Product Confidence Versions

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`[ff750311d30acc9564ef577050794953eee59f01,b02948a23455f8190a53887b2d2c13ae1d360cea)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,9d9c5c218ea356a1d88765214ad2919605280ab1)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,c68e0068a236f9a7dfc19720bdf11e5d80a85089)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,88c673a0bd233df44ca0020da82f4fd3876de27a)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,0cb85377daaefb4ce5ce72975f2deb27ee0e0cad)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,e1ca4e3a380ef3e8f46ce006f1146392e3f32c98)`	affected	code_commit	—
`[ff750311d30acc9564ef577050794953eee59f01,1f7745fb3580152ca902ef181b605f33cabfb1d0)`	affected	code_commit	—

Linux

Linux Kernel

99%

Version	Status	Scheme	Platform
`2.6.39`	affected	semver	—
`[0,2.6.39)`	unaffected	semver	—
`[5.10.271,5.11.0)`	unaffected	semver	—
`[5.15.222,5.16.0)`	unaffected	semver	—
`[6.1.189,6.2.0)`	unaffected	semver	—
`[6.6.158,6.7.0)`	unaffected	semver	—
`[6.12.112,6.13.0)`	unaffected	semver	—
`[6.18.55,6.19.0)`	unaffected	semver	—
`[7.2.9,7.3.0)`	unaffected	semver	—
`[7.3-rc5,*]`	unaffected	generic	—

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Remediation

No solution or workaround provided in the CVE record.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

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Advisories

Source	ID	Title
Debian DLA	DLA-4850-1	linux-6.12 security update

No CVSS v4.0

Attack Vector Local

Attack Complexity Low

Privileges Required High

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

The EPSS score is 0.00176.

Key SSVC decision points have not yet been added.

References

Link	Providers
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98636.mbox
https://git.kernel.org/stable/c/0cb85377daaefb4ce5ce72975f2deb27ee0e0cad
https://git.kernel.org/stable/c/1f7745fb3580152ca902ef181b605f33cabfb1d0
https://git.kernel.org/stable/c/7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1
https://git.kernel.org/stable/c/88c673a0bd233df44ca0020da82f4fd3876de27a
https://git.kernel.org/stable/c/9d9c5c218ea356a1d88765214ad2919605280ab1
https://git.kernel.org/stable/c/b02948a23455f8190a53887b2d2c13ae1d360cea
https://git.kernel.org/stable/c/c68e0068a236f9a7dfc19720bdf11e5d80a85089
https://git.kernel.org/stable/c/e1ca4e3a380ef3e8f46ce006f1146392e3f32c98
https://nvd.nist.gov/vuln/detail/CVE-2026-98636
https://www.cve.org/CVERecord?id=CVE-2026-98636

History

Thu, 22 Oct 2026 12:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-1335
References		https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-98636.mbox https://nvd.nist.gov/vuln/detail/CVE-2026-98636 https://www.cve.org/CVERecord?id=CVE-2026-98636
Metrics	threat_severity `None`	cvssV3_1 `{'score': 4.4, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H'}` threat_severity `Moderate`

Sun, 18 Oct 2026 18:30:00 +0000

Type	Values Removed	Values Added
Weaknesses		CWE-190 CWE-788

Sun, 18 Oct 2026 15:30:00 +0000

Type	Values Removed	Values Added
Description		In the Linux kernel, the following vulnerability has been resolved: squashfs: Add dictionary size range check to prevent shift-out-of-bounds When an abnormal SquashFS image (COMP_OPTS flag is 1 but dictionary size is 0) is mounted, and performs shift operations using dictionarysize, the shift exponent is -1, causing a shift-out-of-bounds. Detail as below: squashfs_comp_opts(msblk, buffer, length) squashfs_xz_comp_opts() if (comp_opts) n = ffs(opts->dict_size) - 1;<----opts->dict_size=0, n=-1 if (opts->dict_size != (1 << n) && opts->dict_size != (1 << n) + (1 << (n + 1))) <----shift-out-of-bounds Fix it by adding a dictionary size range check before the shift operation.
Title		squashfs: Add dictionary size range check to prevent shift-out-of-bounds
First Time appeared		Linux Linux linux Kernel
CPEs		cpe:2.3:o:linux:linux_kernel::::::::
Vendors & Products		Linux Linux linux Kernel
References		https://git.kernel.org/stable/c/0cb85377daaefb4ce5ce72975f2deb27ee0e0cad https://git.kernel.org/stable/c/1f7745fb3580152ca902ef181b605f33cabfb1d0 https://git.kernel.org/stable/c/7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1 https://git.kernel.org/stable/c/88c673a0bd233df44ca0020da82f4fd3876de27a https://git.kernel.org/stable/c/9d9c5c218ea356a1d88765214ad2919605280ab1 https://git.kernel.org/stable/c/b02948a23455f8190a53887b2d2c13ae1d360cea https://git.kernel.org/stable/c/c68e0068a236f9a7dfc19720bdf11e5d80a85089 https://git.kernel.org/stable/c/e1ca4e3a380ef3e8f46ce006f1146392e3f32c98

Subscriptions

Linux Linux Kernel

MITRE

Status: PUBLISHED

Assigner: Linux

Published: 2026-10-18T15:20:07.184Z

Updated: 2026-10-19T09:23:06.005Z

Reserved: 2026-09-25T10:25:14.361Z

Link: CVE-2026-98636

Vulnrichment

No data.

NVD

Status : Received

Published: 2026-10-18T16:17:16.700

Modified: 2026-10-19T10:19:27.837

Link: CVE-2026-98636

Redhat

Severity : Moderate

Publid Date: 2026-10-18T00:00:00Z

Links: CVE-2026-98636 - Bugzilla

OpenCVE Enrichment

Updated: 2026-10-19T07:45:14Z

Weaknesses

Tracking

Attack Vector Local

Attack Complexity Low

Privileges Required High

Scope Unchanged

Confidentiality Impact None

Integrity Impact None

Availability Impact High

User Interaction None

Subscriptions

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