VulnerabilityPublished 19 Nov 2025

CVE-2025-13397: mrubyc · NULL Pointer Dereference

Affects mrubycSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 08:30 UTC

CVSS 4.0 base score

4.8Medium

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 4% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:4.0/AV:L/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X

Attack Vector: Local
Attack Complexity: Low
Attack Requirements: None
Privileges Required: Low
User Interaction: None
Vulnerable system confidentiality: None
Vulnerable system integrity: None
Vulnerable system availability: Low
Subsequent system confidentiality: None
Subsequent system integrity: None
Subsequent system availability: None

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Local: The vulnerable system 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 through terminal emulation (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., using social engineering techniques to trick a legitimate user into opening a malicious document).
Attack Complexity: Low: The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Attack Requirements: None: The successful attack does not depend on the deployment and execution conditions of the vulnerable system. The attacker can expect to be able to reach the vulnerability and execute the exploit under all or most instances of the vulnerability.
Privileges Required: Low: The attacker requires privileges that provide basic capabilities that are typically limited to settings and resources owned by a single low-privileged user. Alternatively, an attacker with Low privileges has the ability to access only non-sensitive resources.
User Interaction: None: The vulnerable system can be exploited without interaction from any human user, other than the attacker.
Vulnerable system confidentiality: None: There is no loss of confidentiality within the Vulnerable System.
Vulnerable system integrity: None: There is no loss of integrity within the Vulnerable System.
Vulnerable system availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the Vulnerable System are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the Vulnerable System.
Subsequent system confidentiality: None: There is no loss of confidentiality within the Subsequent System or all confidentiality impact is constrained to the Vulnerable System.
Subsequent system integrity: None: There is no loss of integrity within the Subsequent System or all integrity impact is constrained to the Vulnerable System.
Subsequent system availability: None: There is no impact to availability within the Subsequent System or all availability impact is constrained to the Vulnerable System.

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 19 Nov 2025
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 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
GitHubmrubyc/mrubyc`pkg:github/mrubyc/mrubyc`Other threats	Affected =3.0 =3.1 =3.2 =3.3 =3.4	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 prioritize applying the official patch identified by commit 009111904807b8567262036bf45297c3da8f1c87 to all affected mrubyc versions (3.0 to 3.4). In environments where patching is delayed, implement strict access controls to limit local user privileges and restrict access to systems running mrubyc to trusted personnel only. Employ monitoring and alerting for abnormal process crashes or system instability that could indicate exploitation attempts. Conduct code audits and testing for any custom scripts or integrations using mrubyc to ensure they do not inadvertently trigger the vulnerability. For embedded devices, coordinate with vendors to ensure firmware updates include the patched mrubyc version. Additionally, consider isolating critical embedded systems from general user environments to reduce the risk of local exploitation. Regularly review and update security policies governing local access and privilege management to minimize the attack surface.

Description

A security vulnerability has been detected in mrubyc up to 3.4. This impacts the function mrbc_raw_realloc of the file src/alloc.c. Such manipulation of the argument ptr leads to null pointer dereference. An attack has to be approached locally. The name of the patch is 009111904807b8567262036bf45297c3da8f1c87. It is advisable to implement a patch to correct this issue.

Impact

For European organizations, the primary impact of CVE-2025-13397 is the risk of denial of service on devices or systems running vulnerable versions of mrubyc. This could disrupt operations in environments where mrubyc is embedded, such as IoT devices, industrial control systems, or specialized automation equipment. Although the vulnerability does not allow privilege escalation or remote code execution, the resulting crashes could lead to downtime, impacting availability and operational continuity. Organizations in sectors with heavy reliance on embedded systems, such as manufacturing, automotive, and telecommunications, may face increased risk. Additionally, service providers utilizing mrubyc in their infrastructure could experience localized outages if the vulnerability is exploited by an insider or a compromised local user. The limited attack vector reduces the likelihood of widespread exploitation but does not eliminate the risk of targeted local attacks or accidental crashes due to malformed inputs.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 26 Nov 2025, 16:03 UTC

Technical details

References

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