CVE-2025-12745VulnerabilityPublished 5 Nov 2025

CVE-2025-12745: QuickJS · Buffer Over-read

Affects QuickJSSource CVE Database V5

Not known to be exploited · CVSS 4.8 Medium.

Data as of 25 Oct 2026, 19:02 UTC

CVSS 4.0 base score

4.8Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 12% 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:L/VI:L/VA:L/SC:N/SI:N/SA:N/E:P

Base metrics

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

Threat metrics

Exploit Maturity: POC

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: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the Vulnerable System.
Vulnerable system integrity: Low: Modification of data is possible, but the attacker does not have control over the consequence of a modification, or the amount of modification is limited. The data modification does not have a direct, serious impact to 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.
Exploit Maturity: POC: Based on threat intelligence sources each of the following must apply: · Proof-of-concept is publicly available · No knowledge of reported attempts to exploit this vulnerability · No knowledge of publicly available solutions used to simplify attempts to exploit the vulnerability

Definitions: FIRST CVSS v4.0 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 5 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 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. Apply the official patch identified by commit c6fe5a98fd3ef3b7064e6e0145dfebfe12449fea immediately to all affected QuickJS instances. 2. Restrict local access to systems running QuickJS to trusted users only, employing strict access controls and monitoring. 3. Employ memory protection mechanisms such as Address Space Layout Randomization (ASLR) and Data Execution Prevention (DEP) to reduce exploitation likelihood. 4. Conduct regular code audits and fuzz testing on QuickJS integrations to detect similar memory safety issues proactively. 5. For embedded or IoT devices using QuickJS, ensure secure firmware update mechanisms to deploy patches efficiently. 6. Monitor local system logs and behavior for unusual activity that could indicate exploitation attempts. 7. Educate developers and system administrators about the risks of local vulnerabilities and the importance of patch management. 8. Consider sandboxing or isolating QuickJS execution environments to limit potential damage from local exploits.

Description

A weakness has been identified in QuickJS up to eb2c89087def1829ed99630cb14b549d7a98408c. This affects the function js_array_buffer_slice of the file quickjs.c. This manipulation causes buffer over-read. The attack is restricted to local execution. The exploit has been made available to the public and could be exploited. This product adopts a rolling release strategy to maintain continuous delivery Patch name: c6fe5a98fd3ef3b7064e6e0145dfebfe12449fea. To fix this issue, it is recommended to deploy a patch.

Impact

For European organizations, the primary impact of CVE-2025-12745 is the potential exposure of sensitive information due to buffer over-read, which compromises confidentiality. While the vulnerability does not allow remote exploitation or privilege escalation, local attackers or malicious insiders could exploit it to access memory contents beyond intended boundaries. This could lead to leakage of cryptographic keys, credentials, or other sensitive data held in memory. Organizations relying on QuickJS in embedded systems, IoT devices, or local development environments may face increased risk, especially if local access controls are weak. The vulnerability does not directly affect system availability or integrity, but information disclosure could facilitate further attacks. European critical infrastructure or sectors with stringent data protection requirements (e.g., finance, healthcare) should prioritize patching to prevent data leakage. The medium severity reflects the limited attack vector but non-negligible confidentiality impact.

Summary

CVE-2025-12745 identifies a buffer over-read vulnerability in the QuickJS JavaScript engine, specifically within the js_array_buffer_slice function in quickjs.c. This flaw allows an attacker with local access and limited privileges to cause the program to read beyond the allocated buffer boundaries, potentially leaking sensitive memory data. The vulnerability arises from improper bounds checking during the slicing operation of ArrayBuffer objects, leading to out-of-bounds memory reads. Exploitation does not require user interaction but does require local code execution privileges, limiting the attack surface primarily to local users or processes. The vulnerability has a CVSS 4.8 (medium) score, reflecting its moderate impact on confidentiality with no direct effect on integrity or availability. QuickJS follows a rolling release model, and a patch identified by commit c6fe5a98fd3ef3b7064e6e0145dfebfe12449fea addresses this issue. Although no active exploitation has been reported, public exploit code is available, increasing the risk of future attacks. The vulnerability is relevant for environments where QuickJS is embedded or used locally, such as development tools, embedded devices, or local scripting environments.

References

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