VulnerabilityPublished 19 Nov 2024Updated 4 Nov 2025

CVE-2024-50273: Linux kernel · btrfs: reinitialize delayed ref list after deleting it from the list

Source GCVE Database

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Not known to be exploited · CVSS 5.5 Medium.

Data as of 30 Oct 2026, 15:50 UTC

CVSS 3.1 base score

5.5Medium

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

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: Low
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
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: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within 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 19 Nov 2024
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: 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 30 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.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), 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-mf47-w2f7-gc7f

What to do

AI-suggested

A fix for this vulnerability has been implemented in the Linux kernel source by replacing list_del() with list_del_init() in the affected code path. Users should apply the official kernel updates that include this fix. Since this is not a cloud service, manual patching is required. No alternative mitigations are indicated by the vendor advisory.

Description

CVE-2024-50273 is a medium-severity vulnerability in the Linux kernel's Btrfs filesystem. It involves improper reinitialization of a delayed reference list after deletion, which can lead to a kernel crash due to invalid list access. The issue arises when a delayed ref is deleted from its list but not properly reinitialized, causing subsequent operations to dereference poisoned pointers. This flaw can cause denial of service via kernel crash but does not impact confidentiality or integrity.

Impact

The vulnerability can cause a denial of service by crashing the Linux kernel when the affected Btrfs code path is exercised. There is no impact on confidentiality or integrity. No known exploits in the wild have been reported. The CVSS v3.1 score is 5.5 (medium), reflecting local attack vector, low complexity, low privileges required, no user interaction, and impact limited to availability.

Summary

The vulnerability in the Linux kernel Btrfs subsystem occurs in the handling of delayed references. When updating an existing reference's action to BTRFS_DROP_DELAYED_REF, the code deletes the reference from its ref head's ref_add_list using list_del(), which sets the list pointers to poison values but does not reinitialize the list structure. Later, if drop_delayed_ref() is called on this reference, it checks list_empty() which returns false due to the uninitialized list, leading to a second list_del() call on poisoned pointers. This results in invalid memory access and a kernel crash, especially when CONFIG_LIST_HARDENED and CONFIG_DEBUG_LIST are enabled. The fix replaces list_del() with list_del_init() to properly reinitialize the list after deletion.

CWE-908Use of Uninitialized Resource (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product uses or accesses a resource that has not been initialized.
Implementation
Explicitly initialize the resource before use. If this is performed through an API function or standard procedure, follow all required steps.
Implementation
Pay close attention to complex conditionals that affect initialization, since some branches might not perform the initialization.
Implementation
Avoid race conditions (CWE-362) during initialization routines.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 30 Oct 2026, 15:50 UTC

WeaknessesCWE-908

Technical details

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