CVE-2023-39804VulnerabilityPublished 27 Mar 2024Updated 4 Nov 2025

CVE-2023-39804: tar · n/a

Affects tarSource CVE Database V5

Not known to be exploited · CVSS 6.2 Medium : upgrade to 1.35 when convenient.

Data as of 26 Oct 2026, 06:26 UTC

CVSS 3.1 base score

6.2Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 20% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch: Available – fixed in 1.35

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

Attack Vector: Local
Attack Complexity: Low
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: 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: 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 27 Mar 2024
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

Upgrade debian/tar to 1.35.

Affected software

Product	Affected	Fixed in
Debiandebian/tar`pkg:deb/debian/tar`Other threats	Affected <1.35	Fixed in 1.35

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

AI-suggested

To mitigate CVE-2023-39804, European organizations should prioritize upgrading GNU tar to version 1.35 or later, where the vulnerability is resolved. Until upgrades are applied, restrict the processing of untrusted or unauthenticated PAX archives, especially from local users or automated systems. Implement file integrity monitoring and logging to detect abnormal crashes or unusual tar activity that may indicate exploitation attempts. Employ access controls to limit local user permissions and reduce the risk of malicious archive injection. In automated pipelines, validate and sanitize archive inputs before processing with GNU tar. Consider using alternative archiving tools with robust security postures if immediate patching is not feasible. Regularly review and update system software inventories to ensure vulnerable versions are identified and remediated promptly. Additionally, educate system administrators about this vulnerability to increase awareness and encourage proactive patch management. For critical systems, implement redundancy and failover mechanisms to minimize downtime caused by potential tar crashes.

Description

In GNU tar before 1.35, mishandled extension attributes in a PAX archive can lead to an application crash in xheader.c.

Impact

The primary impact of CVE-2023-39804 is denial of service through application crashes when processing maliciously crafted PAX archives. For European organizations, this can disrupt automated backup, restore, or deployment workflows that depend on GNU tar, potentially causing operational delays or data availability issues. Organizations with critical infrastructure or services relying on tar for file archiving may experience interruptions affecting business continuity. Although the vulnerability does not compromise confidentiality or integrity, repeated exploitation could degrade system reliability and increase administrative overhead. The requirement for local access limits remote exploitation risk, but insider threats or compromised local accounts could leverage this vulnerability. In environments with high automation and frequent archive handling, such as software development, data centers, and cloud providers, the impact could be more pronounced. European sectors with stringent uptime requirements, including finance, healthcare, and government, may face increased risk from service disruptions. However, the absence of known exploits and the medium severity rating suggest the threat is moderate but warrants timely remediation to prevent potential denial-of-service incidents.

References

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