CVE-2025-6273VulnerabilityPublished 19 Jun 2025Updated 23 Jun 2025

CVE-2025-6273: WebAssembly wabt · Reachable Assertion

Affects WebAssembly wabtSource 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 14% 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: 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

Affected software

Product	Affected	Fixed in
GitHubwebassembly/wabt`pkg:github/webassembly/wabt`Other threats	Affected =1.0.0 =1.0.1 =1.0.2 =1.0.3 =1.0.4 =1.0.5 =1.0.6 =1.0.7 =1.0.8 =1.0.9 =1.0.10 =1.0.11 =1.0.12 =1.0.13 =1.0.14 =1.0.15 =1.0.16 =1.0.17 =1.0.18 =1.0.19 =1.0.20 =1.0.21 =1.0.22 =1.0.23 =1.0.24 =1.0.25 =1.0.26 =1.0.27 =1.0.28 =1.0.29 =1.0.30 =1.0.31 =1.0.32 =1.0.33 =1.0.34 =1.0.35 =1.0.36 =1.0.37	Fixed in–

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

AI-suggested

Update wabt to a version later than 1.0.37 once a patch is released or confirmed by the maintainers to address this assertion issue.

Restrict local access to systems running wabt, especially in shared or multi-user environments, to prevent unauthorized users from triggering the vulnerability.

Implement strict access controls and monitoring on developer workstations and build servers where wabt is used to detect unusual crashes or assertion failures.

Incorporate fuzz testing and input validation in WebAssembly processing workflows to detect malformed or malicious wasm binaries that could trigger assertions.

Consider isolating the execution environment of wabt (e.g., using containers or sandboxing) to limit the impact of potential denial of service conditions.

Engage with the wabt community or maintainers to track updates and confirm the applicability of the vulnerability to your specific use cases and wasm workloads.

Description

A vulnerability was found in WebAssembly wabt up to 1.0.37 and classified as problematic. This issue affects the function LogOpcode of the file src/binary-reader-objdump.cc. The manipulation leads to reachable assertion. Local access is required to approach this attack. The exploit has been disclosed to the public and may be used. The real existence of this vulnerability is still doubted at the moment. The code maintainer explains that this issue might not affect "real world wasm programs".

Impact

For European organizations, the impact of this vulnerability is expected to be limited but non-negligible in specific contexts. Organizations involved in software development, WebAssembly module analysis, or tooling that incorporates wabt could experience local denial of service conditions if an attacker with local access exploits this vulnerability. This could disrupt development workflows or automated build and analysis pipelines. However, since the vulnerability requires local access and does not affect remote execution or compromise data confidentiality or integrity, the risk to critical infrastructure or sensitive data is low. The uncertainty about real-world exploitability further reduces the immediate threat level. Nonetheless, organizations relying on wabt for security-sensitive WebAssembly analysis or embedded in larger toolchains should consider the potential for disruption and the need for patching to maintain operational stability and security hygiene.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 19 Jun 2025, 19:01 UTC

Technical details

References

Community reviews

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