VulnerabilityPublished 18 Oct 2026

CVE-2026-98636: Linux kernel · squashfs: Add dictionary size range check to prevent shift-out-of-bounds

Source GCVE Database

Authoritative record:CVE-2026-98636· Medium

Not known to be exploited · fixed in e1ca4e3a380ef3e8f46ce006f1146392e3f32c98 : update Linux kernel when convenient.

Data as of 26 Oct 2026, 17:16 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in e1ca4e3a380ef3e8f46ce006f1146392e3f32c98, c68e0068a236f9a7dfc19720bdf11e5d80a85089, b02948a23455f8190a53887b2d2c13ae1d360cea +5

Exploitation evidence

Disclosed: evidence found.
CVE published 18 Oct 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 26 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

ghsa-wgfg-84p9-xmpv

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < e1ca4e3a380ef3e8f46ce006f1146392e3f32c98	Fixed in e1ca4e3a380ef3e8f46ce006f1146392e3f32c98
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < c68e0068a236f9a7dfc19720bdf11e5d80a85089	Fixed in c68e0068a236f9a7dfc19720bdf11e5d80a85089
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < b02948a23455f8190a53887b2d2c13ae1d360cea	Fixed in b02948a23455f8190a53887b2d2c13ae1d360cea
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < 88c673a0bd233df44ca0020da82f4fd3876de27a	Fixed in 88c673a0bd233df44ca0020da82f4fd3876de27a
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < 9d9c5c218ea356a1d88765214ad2919605280ab1	Fixed in 9d9c5c218ea356a1d88765214ad2919605280ab1
LinuxLinux	Affected ≥ ff750311d30acc9564ef577050794953eee59f01, < 7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1	Fixed in 7a1c293e7aa17f1afaee0684e0e931fe23a5a6b1

AI-suggested

A fix has been implemented by adding a dictionary size range check before the shift operation in the SquashFS code. Users should apply the official Linux kernel update that includes this patch once available.

Description

A vulnerability in the Linux kernel's SquashFS implementation allows a shift-out-of-bounds operation when mounting an abnormal SquashFS image with a COMP_OPTS flag set to 1 but a dictionary size of 0. This occurs due to missing validation on the dictionary size before performing bit-shift operations, which can lead to an invalid negative shift exponent. The issue has been resolved by adding a dictionary size range check prior to the shift operation.

References

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