VulnerabilityPublished 19 Jun 2025Updated 23 Jun 2025

CVE-2025-6275: WebAssembly wabt · Use After Free

Affects WebAssembly wabtSource CVE Database V5

Public exploit available · CVSS 4.8 Medium.

Data as of 26 Oct 2026, 17:16 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 16% 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:P

Base metrics

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

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: 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.
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 19 Jun 2025
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: evidence found.
CVSS exploit maturity: proof of concept public
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), CVSS vector, 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

Affected software

Product	Affected	Fixed in
GitHubwebassembly/wabt`pkg:github/webassembly/wabt`Other threats	Affected 1.0.0 – 1.0.37 38 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade to the latest version of wabt beyond 1.0.37 once patches are available or monitor official repositories for security updates addressing this vulnerability.
Restrict local access to systems running wabt, especially developer workstations and build servers, to trusted personnel only.
Implement strict access controls and endpoint security measures to prevent unauthorized local access or lateral movement within networks.
Use containerization or sandboxing techniques to isolate wabt usage environments, limiting the impact of any potential exploitation.
Conduct code reviews and static analysis on WebAssembly modules to detect suspicious or malformed inputs that might trigger the vulnerability during testing.
Monitor local system logs and behavior for anomalies that could indicate exploitation attempts, such as unexpected crashes or memory errors related to wabt processes.
Educate developers and security teams about the vulnerability and encourage best practices in handling WebAssembly binaries securely.
Consider alternative WebAssembly toolkits or utilities if immediate patching is not feasible and risk tolerance is low.

Description

A vulnerability was found in WebAssembly wabt up to 1.0.37. It has been declared as problematic. Affected by this vulnerability is the function GetFuncOffset of the file src/interp/binary-reader-interp.cc. The manipulation leads to use after free. It is possible to launch the attack on the local host. The exploit has been disclosed to the public and may be used. A similar issue reported during the same timeframe was disputed by the code maintainer because it might not affect "real world wasm programs". Therefore, this entry might get disputed as well in the future.

Impact

For European organizations, the direct impact of CVE-2025-6275 is relatively limited due to the requirement for local access and the medium severity rating. However, organizations heavily involved in WebAssembly development, research, or deployment could face risks such as local privilege escalation or denial of service if an attacker gains local access to developer machines or build servers running vulnerable wabt versions. This could lead to disruption of development workflows or potential compromise of sensitive code or intellectual property. Since WebAssembly is increasingly used in web applications and cloud environments, any compromise in the toolchain could indirectly affect software supply chain integrity. Critical sectors such as finance, telecommunications, and technology companies in Europe that leverage WebAssembly for performance or security benefits might be more sensitive to disruptions. The lack of known active exploitation reduces immediate risk, but the public disclosure means attackers could develop exploits targeting vulnerable local environments. The disputed real-world impact suggests that the threat might be more theoretical than practical, but cautious organizations should not dismiss the risk entirely.

Summary

CVE-2025-6275 is a use-after-free vulnerability identified in the WebAssembly Binary Toolkit (wabt) up to version 1.0.37. The flaw exists specifically in the function GetFuncOffset within the source file src/interp/binary-reader-interp.cc. This vulnerability arises when the function improperly manages memory, leading to a use-after-free condition where a previously freed memory region is accessed. Such a flaw can cause undefined behavior including crashes, data corruption, or potentially arbitrary code execution. The vulnerability requires local access to the host system to be exploited, meaning an attacker must have some level of local privileges (low privileges) to trigger the flaw. No user interaction or authentication is required beyond local access. The vulnerability has a CVSS 4.0 base score of 4.8, categorized as medium severity, reflecting limited impact and exploitation complexity. The exploit has been publicly disclosed but there are no known exploits actively used in the wild. Additionally, the maintainer has disputed the practical impact of a similar issue, suggesting that real-world WebAssembly programs may not be affected, which could also apply to this vulnerability. Wabt is a widely used toolkit for WebAssembly development and debugging, often employed by developers and security researchers to inspect, manipulate, and validate WebAssembly binaries. The vulnerability could impact any environment where vulnerable versions of wabt are used locally, especially in development or testing scenarios involving WebAssembly modules.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 Jun 2025, 19:42 UTC

Technical details

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