Linux Kernel up to 7.1.4 jbd2 jbd2_journal_initialize_fast_commit num_fc_blks integer underflow

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
5.2	$0-$5k	0.00

Summaryinfo

A vulnerability categorized as problematic has been discovered in Linux Kernel up to 7.1.4. This affects the function jbd2_journal_initialize_fast_commit of the component jbd2. The manipulation of the argument num_fc_blks results in integer underflow. This vulnerability is reported as CVE-2026-72225. The attack can be launched remotely. No exploit exists.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.1.4. It has been classified as problematic. Affected is the function jbd2_journal_initialize_fast_commit of the component jbd2. The manipulation of the argument num_fc_blks with an unknown input leads to a integer underflow vulnerability. CWE is classifying the issue as CWE-191. The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result. This is going to have an impact on integrity, and availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: jbd2: fix integer underflow in jbd2_journal_initialize_fast_commit() jbd2_journal_initialize_fast_commit() validates journal capacity by checking (journal->j_last - num_fc_blks < JBD2_MIN_JOURNAL_BLOCKS). Both j_last and num_fc_blks are unsigned, so when num_fc_blks exceeds j_last the subtraction wraps to a large value, bypassing the bounds check. The resulting underflow corrupts j_last, j_fc_first, and j_free, leading to journal abort. Fix by checking num_fc_blks against j_last before the subtraction, returning -EFSCORRUPTED.

The advisory is shared for download at git.kernel.org. This vulnerability is traded as CVE-2026-72225 since 08/09/2026. The exploitability is told to be easy. It is possible to launch the attack remotely. There are known technical details, but no exploit is available. The current price for an exploit might be approx. USD $0-$5k (estimation calculated on 08/15/2026).

The vulnerability scanner Nessus provides a plugin with the ID 335741 (Linux Distros Unpatched Vulnerability : CVE-2026-72225), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.15.212, 6.1.178, 6.6.145, 6.12.97, 6.18.40, 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch e144ad0250f77e23e28949587b8b57e40dc3b512/4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6/fb9b49618ed7296ebfad62a3835da8945f727001/4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9/78955fdce8ff654e6d33a2fa90882a1e7eb26330/a58fc10adf503969fec2007b5afe8987258046c4/289a2ca0c9b7eae74f93fc213b0b971669b8683d is able to eliminate this problem.

The vulnerability is also documented in the vulnerability database at Tenable (335741). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.15.211
• 6.1.177
• 6.6.144
• 6.12.0
• 6.12.1
• 6.12.2
• 6.12.3
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• 6.12.94
• 6.12.95
• 6.12.96
• 6.18.0
• 6.18.1
• 6.18.2
• 6.18.3
• 6.18.4
• 6.18.5
• 6.18.6
• 6.18.7
• 6.18.8
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• 6.18.35
• 6.18.36
• 6.18.37
• 6.18.38
• 6.18.39
• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

• 🔒
• 🔒
• 🔒

CPE 2.2info

• 🔒
• 🔒
• 🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 5.4
VulDB Meta Temp Score: 5.2

VulDB Base Score: 5.4
VulDB Temp Score: 5.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Integer underflow
CWE: CWE-191 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Nessus ID: 335741
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-72225

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 5.15.212/6.1.178/6.6.145/6.12.97/6.18.40/7.1.5/7.2-rc1
Patch: e144ad0250f77e23e28949587b8b57e40dc3b512/4b48dcb88bb9117e3d3f051175a9a8b7cff7f8b6/fb9b49618ed7296ebfad62a3835da8945f727001/4450dcaadf7d4aae8b6e4223b5d6ee4eb77097a9/78955fdce8ff654e6d33a2fa90882a1e7eb26330/a58fc10adf503969fec2007b5afe8987258046c4/289a2ca0c9b7eae74f93fc213b0b971669b8683d

Timelineinfo

08/09/2026 CVE reserved
08/15/2026 +6 days Advisory disclosed
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-72225 (🔒)
GCVE (CVE): GCVE-0-2026-72225
GCVE (VulDB): GCVE-100-390552

Entryinfo

Created: 08/15/2026 12:44
Updated: 08/15/2026 21:27
Changes: 08/15/2026 12:44 (60), 08/15/2026 21:27 (2)
Complete: 🔍
Cache ID: 216::103

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