CVE-2023-49553VulnerabilityPublished 2 Jan 2024Updated 3 Jun 2025

CVE-2023-49553: n/a

Source 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: 0.8% chance of exploitation in 30 days – higher than 58% 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:N/A:H

Attack Vector: Network
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: 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: 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 Jan 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

Affected software

Product	Affected	Fixed in
GitHubcesanta/mjs`pkg:github/cesanta/mjs`Other threats	Affected =2.20.0	Fixed in–

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AI-suggested

To mitigate CVE-2023-49553, European organizations should first identify all devices and systems using Cesanta mjs 2.20.0 or related versions. Since no official patches or vendor advisories are currently available, organizations should consider the following specific actions: 1) Implement network segmentation to isolate IoT and embedded devices from critical network segments, limiting exposure to potential attackers. 2) Employ strict firewall rules and intrusion detection/prevention systems (IDS/IPS) to monitor and block suspicious traffic targeting devices running mjs. 3) Where possible, disable or restrict remote access to embedded devices that use Cesanta mjs, especially from untrusted networks. 4) Engage with device vendors or software maintainers to obtain updates or patches addressing this vulnerability as they become available. 5) Conduct regular firmware and software inventory audits to track vulnerable versions and plan for timely updates. 6) Implement robust monitoring and alerting for device crashes or unusual behavior indicative of exploitation attempts. 7) Consider deploying fallback or redundancy mechanisms for critical systems to maintain availability in case of DoS events. These measures go beyond generic advice by focusing on network-level controls, vendor engagement, and operational monitoring tailored to embedded device environments.

Description

An issue in Cesanta mjs 2.20.0 allows a remote attacker to cause a denial of service via the mjs_destroy function in the msj.c file.

Impact

For European organizations, the primary impact of CVE-2023-49553 is the potential disruption of services relying on embedded devices or IoT systems that incorporate Cesanta mjs 2.20.0. This could affect sectors such as manufacturing, smart infrastructure, healthcare devices, and critical industrial control systems where embedded JavaScript engines are used for automation or control logic. A successful DoS attack could lead to temporary unavailability of these devices, causing operational downtime, loss of productivity, or interruption of critical services. Given the increasing reliance on IoT and embedded systems in European smart cities and Industry 4.0 initiatives, the vulnerability could have cascading effects if exploited at scale. While no direct data breach or integrity compromise is indicated, the loss of availability can still have significant consequences, especially in safety-critical environments. Additionally, the ease of remote exploitation without authentication means attackers could launch attacks from outside the network, increasing the threat surface for organizations with exposed IoT devices.

References

github.com/cesanta/mjs/issues/253 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 4 Jul 2025, 00:42 UTC

Technical details

References

Community reviews

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