CVE-2023-49298VulnerabilityPublished 24 Nov 2023Updated 3 Nov 2025

CVE-2023-49298: zfs · n/a

Affects zfsSource CVE Database V5

Not known to be exploited · CVSS 7.5 High.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

7.5High

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

EPSS: 1.1% chance of exploitation in 30 days – higher than 66% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

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

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: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
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: 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: None: There is no impact to availability within the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Nov 2023
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 2026-10-26.

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

Affected software

Product	Affected	Fixed in
GitHubopenzfs/zfs`pkg:github/openzfs/zfs`Other threats	Affected <=2.1.13 >=2.2.0 <=2.2.1	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

European organizations should immediately assess their use of OpenZFS versions up to 2.1.13 and 2.2.x through 2.2.1 and plan for prompt upgrades to versions beyond 2.2.1 where the issue is less prevalent or fully patched once available. Until patches are applied, organizations should implement strict integrity verification of critical configuration and security files after any copy or backup operations, using cryptographic hashes or file integrity monitoring tools. Avoid relying solely on OpenZFS's efficient copy mechanisms for security-sensitive files; instead, use verified copy methods that ensure data correctness. Review and harden file copy workflows, especially those involving GNU coreutils cp or similar utilities, to detect and prevent zero-byte file replacements. Employ monitoring and alerting on unexpected changes to critical files like /etc/hosts.deny or access control lists. Limit network exposure of systems running vulnerable OpenZFS versions and restrict access to trusted users only. Finally, maintain up-to-date backups and test restoration procedures to recover from potential silent data corruption incidents.

Description

OpenZFS through 2.1.13 and 2.2.x through 2.2.1, in certain scenarios involving applications that try to rely on efficient copying of file data, can replace file contents with zero-valued bytes and thus potentially disable security mechanisms. NOTE: this issue is not always security related, but can be security related in realistic situations. A possible example is cp, from a recent GNU Core Utilities (coreutils) version, when attempting to preserve a rule set for denying unauthorized access. (One might use cp when configuring access control, such as with the /etc/hosts.deny file specified in the IBM Support reference.) NOTE: this issue occurs less often in version 2.2.1, and in versions before 2.1.4, because of the default configuration in those versions.

Impact

For European organizations, the impact of CVE-2023-49298 can be substantial, especially in sectors that rely heavily on OpenZFS for data storage and integrity, such as government, finance, telecommunications, and critical infrastructure. The vulnerability can lead to unauthorized modification of critical configuration files or security policies by replacing their contents with zeros, effectively disabling security controls without detection. This can result in unauthorized access, privilege escalation, or denial of security enforcement, undermining the confidentiality and integrity of sensitive data. Since the vulnerability does not affect availability directly, service disruption is less likely, but the silent corruption of security-related files poses a serious risk. Organizations using automated file copy operations or backup tools that rely on OpenZFS's efficient copying mechanisms are particularly vulnerable. The lack of required authentication and user interaction means attackers can exploit this remotely if they can trigger file copy operations, increasing the threat surface. The absence of known exploits in the wild provides a window for proactive mitigation, but the high CVSS score underscores the urgency of addressing this issue.

Summary

CVE-2023-49298 is a vulnerability affecting OpenZFS storage systems in versions up to 2.1.13 and 2.2.x through 2.2.1. The issue manifests during certain file copy operations where applications depend on efficient data copying mechanisms provided by OpenZFS. Under these conditions, the file contents can be replaced with zero-valued bytes instead of the expected data. This behavior can inadvertently disable security controls that rely on file contents, such as access control lists or deny rules configured in files like /etc/hosts.deny. The vulnerability is linked to improper handling of file data during copy-on-write or similar operations, categorized under CWE-639 (Authorization Bypass Through User-Controlled Key). While not always security-critical, realistic scenarios exist where this can lead to security bypasses. The flaw is less prevalent in version 2.2.1 and earlier than 2.1.4 due to default configuration changes that mitigate the issue. The CVSS 3.1 score of 7.5 reflects a network attack vector with low attack complexity, no privileges or user interaction required, and a high impact on integrity but no impact on confidentiality or availability. No public exploits have been reported yet, but the potential for disabling critical security mechanisms makes this a significant risk for systems relying on OpenZFS for secure file storage and copying.

CWE-639Authorization Bypass Through User-Controlled Key (opens in a new tab)
Base weaknessLikelihood of exploit: HighCWE Top 25 (2025): #24OWASP Top 10 A01:2025: Broken Access Control (opens in a new tab)
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.
Architecture and Design
For each and every data access, ensure that the user has sufficient privilege to access the record that is being requested.
Architecture and Design · Implementation
Make sure that the key that is used in the lookup of a specific user's record is not controllable externally by the user or that any tampering can be detected.
Architecture and Design
Use encryption in order to make it more difficult to guess other legitimate values of the key or associate a digital signature with the key so that the server can verify that there has been no tampering.
OWASP Cheat Sheets
Access Control (opens in a new tab)
Authorization Testing Automation (opens in a new tab)
Cross-Site Request Forgery Prevention (opens in a new tab)
Insecure Direct Object Reference Prevention (opens in a new tab)
Authorization (opens in a new tab)
OWASP ASVS 4.0.3
V4.1.2 (opens in a new tab)
V4.2.1 (opens in a new tab)
V8.3.8 (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Nov 2025, 19:52 UTC

WeaknessesCWE-639

Technical details

References

Community reviews

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