CVE-2023-32253VulnerabilityPublished 2 Aug 2025Updated 20 Nov 2025

CVE-2023-32253: Improper Resource Locking

Source CVE Database V5

Not known to be exploited · CVSS 5.9 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

5.9Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 23% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Network
Attack Complexity: High
Privileges Required: None
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: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, 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: High: A successful attack depends on conditions beyond the attacker's control. That is, a successful attack cannot be accomplished at will, but requires the attacker to invest in some measurable amount of effort in preparation or execution against the vulnerable component before a successful attack can be expected. For example, a successful attack may require an attacker to: gather knowledge about the environment in which the vulnerable target/component exists; prepare the target environment to improve exploit reliability; or inject themselves into the logical network path between the target and the resource requested by the victim in order to read and/or modify network communications (e.g., a man in the middle attack).
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
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 2 Aug 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.

What to do

AI-suggested

To mitigate CVE-2023-32253, organizations should prioritize applying official Linux kernel patches addressing the ksmbd deadlock vulnerability once available from their Linux distribution vendors. Until patches are deployed, network administrators should restrict access to SMB services by implementing strict firewall rules to limit exposure only to trusted internal networks. Disabling ksmbd or SMB services on Linux systems where not required can reduce attack surface. Monitoring network traffic for unusual spikes in SMB session setup requests may help detect exploitation attempts. Employing network segmentation to isolate SMB servers and using VPNs or secure tunnels for remote SMB access can further reduce risk. Regularly updating Linux kernels and maintaining an inventory of systems running ksmbd will aid in timely vulnerability management. Additionally, organizations should review and harden SMB configurations to minimize unnecessary service exposure.

Description

CVE-2023-32253 is a medium severity vulnerability in the Linux kernel's ksmbd component that can cause a denial of service via a deadlock triggered by multiple concurrent session setup requests. It affects Linux kernel versions from 0 up to 6.3.0. The flaw does not impact confidentiality or integrity but can severely impact availability by halting the affected service. Exploitation requires network access but no authentication or user interaction. No known exploits are currently reported in the wild. European organizations relying on Linux servers with ksmbd enabled, especially those using SMB services, are at risk of service disruption. Mitigation involves applying kernel patches once available and limiting exposure of SMB services to untrusted networks. Countries with significant Linux server deployments and critical infrastructure using SMB are more likely to be impacted.

Impact

For European organizations, the primary impact of CVE-2023-32253 is the potential denial of service on Linux servers running the ksmbd SMB server component. This can disrupt file sharing, network-attached storage, and other SMB-dependent services critical to business operations. Availability loss can affect internal collaboration, data access, and potentially business continuity if SMB services are integral to workflows. Organizations in sectors such as finance, manufacturing, public administration, and critical infrastructure that rely on Linux-based SMB servers are particularly at risk. The vulnerability does not expose data to theft or modification but can cause operational downtime. Given the medium CVSS score and the requirement for high attack complexity, widespread exploitation is less likely but targeted attacks against exposed SMB services could cause localized outages. The lack of authentication requirement means attackers can attempt exploitation from any network location with access to the SMB service, increasing risk if SMB ports are exposed externally or insufficiently segmented internally.

Summary

CVE-2023-32253 is a vulnerability identified in the ksmbd component of the Linux kernel, which implements the SMB (Server Message Block) protocol server functionality. The flaw arises from improper resource locking mechanisms within ksmbd, specifically when handling multiple concurrent session setup requests. An attacker can send numerous simultaneous session setup requests to the vulnerable kernel, causing a deadlock condition. This deadlock halts the ksmbd service, resulting in a denial of service (DoS) where legitimate SMB clients cannot establish or maintain sessions. The vulnerability affects Linux kernel versions starting from 0 up to and including 6.3.0, indicating a broad range of impacted systems. The CVSS 3.1 base score is 5.9, with vector AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H, meaning the attack can be performed remotely over the network but requires high attack complexity, no privileges or user interaction, and impacts only availability. No confidentiality or integrity impact is noted. As ksmbd is used to provide SMB services on Linux, systems running file sharing or network storage services using this kernel component are vulnerable. No known exploits have been reported in the wild, but the potential for DoS disruption exists if exploited. The vulnerability was published on August 2, 2025, and assigned by Red Hat. No patches or exploit indicators are currently provided in the data, but kernel maintainers are expected to release fixes given the severity and impact.

References

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