VulnerabilityPublished 2 Jan 2024Updated 3 Jun 2025

CVE-2023-49558

Source CVE Database V5

Not known to be exploited · CVSS 5.5 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

5.5Medium

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

EPSS: 0.3% chance of exploitation in 30 days – higher than 31% 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:N/I:N/A:H

Attack Vector: Local
Attack Complexity: Low
Privileges Required: None
User Interaction: Required
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: 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: 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 26 Oct 2026.

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 or the CVSS exploit maturity 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 this vulnerability, European organizations should first identify all instances of YASM 1.3.0.86.g9def in their environments, particularly within development and build systems. Since no official patches are currently available, organizations should consider the following specific actions: 1) Restrict local access to systems running YASM to trusted users only, minimizing the risk of unauthorized local exploitation. 2) Implement strict user interaction policies and monitor for unusual activity involving YASM processes. 3) Where feasible, replace or upgrade YASM to a later version if available, or apply community patches if any exist. 4) Integrate YASM execution within sandboxed or containerized environments to limit the impact of potential crashes. 5) Enhance logging and monitoring around build systems to quickly detect and respond to denial of service symptoms. 6) Coordinate with software supply chain teams to assess dependencies on YASM and prepare contingency plans for build disruptions. 7) Engage with the open-source community or maintainers of YASM for updates or patches addressing this vulnerability.

Description

An issue in YASM 1.3.0.86.g9def allows a remote attacker to cause a denial of service via the expand_mmac_params function in the modules/preprocs/nasm/nasm-pp.c component.

Impact

For European organizations, the primary impact of this vulnerability lies in disruption of software development and build processes that rely on YASM. Organizations involved in software development, embedded systems, or reverse engineering that use YASM could experience denial of service conditions, leading to delays in build pipelines or analysis tasks. While this does not directly compromise data confidentiality or integrity, the availability impact can affect operational efficiency and project timelines. In critical infrastructure or industries with stringent development cycles (e.g., automotive, aerospace, telecommunications), such disruptions could cascade into broader operational delays. However, since exploitation requires local access and user interaction, the risk of widespread remote attacks is limited. Organizations with strict access controls and user policies may face lower risk. The absence of known exploits reduces immediate threat levels but does not eliminate the need for vigilance, especially in environments where YASM is integrated into automated build or continuous integration systems.

References

github.com/yasm/yasm/issues/252 (opens in a new tab)

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 4 Jul 2025, 05:39 UTC

Technical details

References

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