CVE-2023-43787VulnerabilityPublished 10 Oct 2023Updated 6 Nov 2025

CVE-2023-43787: Heap-based Buffer Overflow

Source CVE Database V5

Not known to be exploited · CVSS 7.8 High.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 3.1 base score

7.8High

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 40% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
Scope: Unchanged
Confidentiality: High
Integrity: High
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: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
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: High: There is 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.
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: 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 10 Oct 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 2026-10-25.

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

1. Immediately restrict local access to systems running libX11, especially for untrusted users or processes. 2. Implement strict user privilege separation and enforce the principle of least privilege to minimize the risk of local exploitation. 3. Monitor system logs and user activity for unusual behavior indicative of exploitation attempts, such as unexpected crashes or memory errors related to X11 processes. 4. Apply security patches promptly once they become available from libX11 maintainers or Linux distribution vendors. 5. Consider deploying application whitelisting or sandboxing techniques to limit the impact of potential code execution. 6. Educate users about the risks of executing untrusted code or opening suspicious files that might trigger the vulnerability. 7. For critical environments, evaluate the feasibility of temporarily disabling or limiting X11 usage until patches are applied. 8. Employ host-based intrusion detection systems (HIDS) to detect anomalous activities related to this vulnerability.

Description

A vulnerability was found in libX11 due to an integer overflow within the XCreateImage() function. This flaw allows a local user to trigger an integer overflow and execute arbitrary code with elevated privileges.

Impact

For European organizations, this vulnerability poses a significant risk primarily to systems running Linux or Unix-like operating systems with graphical environments relying on libX11. Successful exploitation could lead to full system compromise by local attackers, allowing them to escalate privileges, execute arbitrary code, and potentially move laterally within networks. This threatens the confidentiality of sensitive data, the integrity of system operations, and the availability of critical services. Organizations with development workstations, research labs, or user environments where local access is possible are particularly vulnerable. The impact is heightened in sectors with stringent data protection requirements such as finance, healthcare, and government institutions across Europe. Additionally, the vulnerability could be leveraged in targeted attacks or insider threat scenarios. Although no known exploits are currently active, the high severity and ease of exploitation once local access is obtained make this a pressing concern.

References

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