CVE-2025-40349VulnerabilityPublished 16 Dec 2025Updated 30 Jul 2026

CVE-2025-40349: Linux kernel · hfs: validate record offset in hfsplus_bmap_alloc hfsplus_bmap_alloc can trigger

Source GCVE Database

Not known to be exploited · CVSS 7.8 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

7.8High

How severe the flaw is on the 0–10 CVSS scale.

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: High
Integrity: High
Availability: High

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable component is not bound to the network stack and the attacker’s path is via read/write/execute capabilities. Either: the attacker exploits the vulnerability by accessing the target system locally (e.g., keyboard, console), or remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component.
Availability: High: There is total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable).

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 16 Dec 2025
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 2026-10-25.

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 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-fw43-f4rv-3fjg

What to do

AI-suggested

A patch has been applied to the Linux kernel to validate record offset and length in hfsplus_bmap_alloc, preventing out-of-bounds memory access. Users and administrators should update to the fixed Linux kernel version once available. Patch status is not explicitly confirmed in the provided data, so check the official Linux kernel advisories or vendor sources for the exact fixed versions and apply updates accordingly.

Description

A vulnerability in the Linux kernel's HFS+ filesystem implementation (hfsplus_bmap_alloc) allows out-of-bounds memory access due to improper validation of record offset and length. This can cause a kernel crash (KASAN slab-out-of-bounds) and potentially lead to high impact including confidentiality, integrity, and availability loss. The issue arises when the offset or length exceeds the node size, leading to invalid page access. A patch has been applied to add proper validation of these values to prevent out-of-bounds access.

Impact

Exploitation of this vulnerability can cause a kernel crash resulting in denial of service. The CVSS vector indicates local attack vector with low complexity and low privileges required, no user interaction, and impacts confidentiality, integrity, and availability at a high level. This means an attacker with local access and limited privileges could trigger the vulnerability to crash the system and potentially affect data confidentiality and integrity.

Summary

The Linux kernel's hfsplus_bmap_alloc function in the HFS+ filesystem code did not properly validate the record offset and length before using them to access memory pages. If these values exceeded the node size, the function could access memory outside the allocated node range, causing a slab-out-of-bounds error detected by KASAN and leading to a kernel crash. The vulnerability is addressed by adding validation checks for offset and length before use, preventing out-of-bounds page access. This fix moves validation helper functions to a shared header for broader use.

References

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