CVE-2025-3500VulnerabilityPublished 12/01/2025Updated 02/26/2026

CVE-2025-3500: Avast Antivirus · Integer Overflow or Wraparound

Affects Avast AntivirusSource CVE Database V5

Not known to be exploited · CVSS 9.0 Critical.

Data as of 10/25/2026, 16:36:12 UTC

CVSS 3.1 base score

9.0Critical

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

EPSS: 0.4% chance of exploitation in 30 days – higher than 39% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Attack Vector: Network
Attack Complexity: Low
Privileges Required: Low
User Interaction: Required
Scope: Changed
Confidentiality: High
Integrity: High
Availability: High

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

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: Low: The attacker is authorized with (i.e., requires) privileges that provide basic user capabilities that could normally affect only settings and files owned by a user. Alternatively, an attacker with Low privileges may have the ability to cause an impact only to non-sensitive resources.
User Interaction: Required: Successful exploitation of this vulnerability requires a user to take some action before the vulnerability can be exploited.
Scope: Changed: An exploited vulnerability can affect resources beyond the security scope managed by the security authority of the vulnerable component. In this case, the vulnerable component and the impacted component are different and managed by different security authorities.
Confidentiality: High: There is total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact.
Integrity: High: There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to 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 1 Dec 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 wild: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq 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
Avast Antivirus	Affected =25.1.981.6	Fixed in–

AI-suggested

1. Immediately audit and inventory all systems running Avast Antivirus versions 25.1.981.6 through before 25.3 to identify vulnerable endpoints. 2. Apply vendor patches or upgrade to Avast Antivirus version 25.3 or later as soon as they become available to remediate the integer overflow vulnerability. 3. Restrict local user privileges to the minimum necessary, preventing unprivileged users from executing code or performing actions that could trigger the vulnerability. 4. Implement application whitelisting and endpoint detection and response (EDR) solutions to monitor and block suspicious activities indicative of privilege escalation attempts. 5. Educate users about the risks of interacting with untrusted content or executing unknown applications, as user interaction is required for exploitation. 6. Monitor system and security logs for unusual privilege escalation events or anomalies related to Avast Antivirus processes. 7. Employ network segmentation to limit lateral movement if a local compromise occurs. 8. Prepare incident response plans specifically addressing potential exploitation of antivirus software vulnerabilities. 9. Coordinate with Avast support or security advisories for timely updates and additional mitigation guidance. 10.

Description

Integer Overflow or Wraparound vulnerability in Avast Antivirus (25.1.981.6) on Windows allows Privilege Escalation.This issue affects Antivirus: from 25.1.981.6 before 25.3.

Impact

The impact of CVE-2025-3500 is severe for organizations worldwide using Avast Antivirus on Windows. Successful exploitation allows local attackers to escalate privileges, potentially gaining administrative or SYSTEM-level access. This can lead to full compromise of affected endpoints, enabling attackers to install persistent malware, exfiltrate sensitive data, disable security controls, or move laterally within networks. The vulnerability affects confidentiality, integrity, and availability of systems, as attackers can manipulate or destroy data, disrupt operations, or hide malicious activities. Since antivirus software is a trusted security component, its compromise undermines overall security posture and can facilitate further attacks. Organizations with large Windows deployments and reliance on Avast Antivirus, especially in sectors like finance, healthcare, government, and critical infrastructure, face heightened risk. The need for user interaction and local access somewhat limits remote exploitation but does not eliminate risk, particularly in environments with many users or where attackers have initial footholds. The absence of known exploits in the wild currently reduces immediate threat but does not diminish urgency for remediation due to the critical severity and potential for rapid weaponization.

Weaknesses

CWE-190Integer Overflow or Wraparound (opens in a new tab)
Base weaknessLikelihood of exploit: Medium
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.
Requirements
Ensure that all protocols are strictly defined, such that all out-of-bounds behavior can be identified simply, and require strict conformance to the protocol.
Requirements · Language Selection
Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
Architecture and Design · Libraries or Frameworks
Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V5.4.3 (opens in a new tab)
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
Attack patterns
Forced Integer Overflow (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

gendigital.com/us/en/contact-us/security-advisories/ (opens in a new tab)

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