CVE-2026-74723 : 詳細

CVE-2026-74723

9.8
/
緊急
2026-08-22
16h16 +00:00
Network
2026-10-30
13h20 +00:00
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CVE の説明

In the Linux kernel, the following vulnerability has been resolved: btrfs: lzo: reject inline extents without valid headers [BUG] For a crafted btrfs image, the following KASAN can be triggered when reading an inline lzo compressed file extent: BUG: KASAN: slab-out-of-bounds in lzo_decompress+0x57d/0x700 Read of size 4 at addr ffff888006f2e644 by task btrfs_lzo_inlin/77 Call Trace: dump_stack_lvl+0x5b/0x70 print_report+0xd1/0x610 kasan_report+0xe0/0x110 __asan_report_load_n_noabort+0x13/0x20 lzo_decompress+0x57d/0x700 btrfs_decompress+0x140/0x1c0 uncompress_inline+0x147/0x1b0 btrfs_get_extent+0xb23/0x10a0 btrfs_do_readpage.constprop.0+0x538/0x1ac0 btrfs_readahead+0x32f/0x5f0 read_pages+0x16f/0x850 page_cache_ra_unbounded+0x296/0x490 do_page_cache_ra+0xd9/0x130 page_cache_sync_ra+0x3ee/0x6f0 filemap_get_pages+0x306/0x15c0 filemap_read+0x329/0xd00 btrfs_file_read_iter+0x1f8/0x2b0 vfs_read+0x4ef/0x720 ksys_read+0xf8/0x1d0 __x64_sys_read+0x71/0xb0 x64_sys_call+0x1ab0/0x1b70 do_syscall_64+0x61/0x470 entry_SYSCALL_64_after_hwframe+0x4b/0x53 [CAUSE] For an inline lzo compressed file extent, there should always be one lzo header, recording the total length of the compressed data, followed by one segment header, recording the compressed lzo payload. But if a crafted inline lzo compressed file extent contains only an lzo header, without the segment header or payload, lzo_decompress() will still try to read the segment header, causing a read beyond the item boundary. Furthermore if the inline lzo compressed file extent is the first item of the leaf, it will be at the extent buffer boundary. The above out-of-boundary read will go beyond the extent buffer boundary, triggering the above KASAN report. [FIX] Validate the total length of the inlined lzo compressed file extent, to make sure there is at least one LZO header and one segment header, and a non-zero payload. [ Rework the commit message to remove slop ]

CVE の情報

メトリクス

メトリクス スコア 深刻度 CVSS ベクター 出典
V3.1 9.8 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Base: Exploitabilty Metrics

The Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component.

Attack Vector

This metric reflects the context by which vulnerability exploitation is possible.

Network

The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).

Attack Complexity

This metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability.

Low

Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component.

Privileges Required

This metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability.

None

The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.

User Interaction

This metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component.

None

The vulnerable system can be exploited without interaction from any user.

Base: Scope Metrics

The Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope.

Scope

Formally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs.

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.

Base: Impact Metrics

The Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve.

Confidentiality Impact

This metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability.

High

There is a 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. For example, an attacker steals the administrator's password, or private encryption keys of a web server.

Integrity Impact

This metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information.

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 Impact

This metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability.

High

There is a 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).

Temporal Metrics

The Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability.

Environmental Metrics

These metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.

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