VulnerabilityPublished 30 Jul 2025Updated 14 Aug 2025

CVE-2025-4423: Insyde Software InsydeH2O · Memory Buffer Overflow

Affects Insyde Software InsydeH2OSource CVE Database V5

Not known to be exploited · CVSS 8.2 High.

Data as of 26 Oct 2026, 17:16 UTC

CVSS 3.1 base score

8.2High

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

EPSS: 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Local
Attack Complexity: Low
Privileges Required: High
User Interaction: None
Scope: Changed
Confidentiality: High
Integrity: High
Availability: High

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

Attack Vector: Local: The vulnerable component 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 remotely (e.g., SSH); or the attacker relies on User Interaction by another person to perform actions required to exploit the vulnerability (e.g., tricking a legitimate user into opening a malicious document).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: High: The attacker is authorized with (i.e., requires) privileges that provide significant (e.g., administrative) control over the vulnerable component that could affect component-wide settings and files.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
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 30 Jul 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 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

AI-suggested

Monitor Lenovo's official Product Security Advisories closely for firmware updates or patches addressing CVE-2025-4423 and apply them promptly once available.
Implement strict access controls to limit local administrative privileges on Lenovo devices, reducing the risk of attackers obtaining the high privileges required for exploitation.
Employ endpoint detection and response (EDR) solutions capable of monitoring firmware integrity and suspicious local privilege escalation activities.
Enforce physical security measures to prevent unauthorized local access to devices, including secure storage and access logging.
Conduct regular security audits and vulnerability assessments focusing on firmware versions and configurations of Lenovo devices.
Consider deploying hardware-based security features such as Trusted Platform Module (TPM) and secure boot to detect unauthorized firmware modifications.
Educate IT staff and users about the risks of local privilege escalation vulnerabilities and the importance of reporting suspicious activities promptly.
Prepare incident response plans that include firmware compromise scenarios to ensure rapid containment and recovery.

Description

The vulnerability was identified in the code developed specifically for Lenovo. Please visit "Lenovo Product Security Advisories and Announcements" webpage for more information about the vulnerability. https://support.lenovo.com/us/en/product_security/home

Impact

For European organizations using Lenovo hardware with the vulnerable InsydeH2O firmware, this vulnerability poses a significant risk. Given the BIOS/UEFI level of the flaw, attackers with local high privileges could gain persistent, stealthy control over affected devices, undermining confidentiality, integrity, and availability of critical systems. This could lead to data breaches, sabotage of business operations, or espionage, especially in sectors with sensitive information such as finance, government, healthcare, and critical infrastructure. The requirement for local high privileges limits remote exploitation but insider threats or attackers who gain initial footholds via other means could leverage this vulnerability to escalate privileges and maintain persistence. The impact is heightened by the firmware layer's difficulty to detect and remediate without firmware updates or hardware replacement. European organizations relying heavily on Lenovo hardware in their IT infrastructure must consider this vulnerability a serious threat to endpoint security and overall cyber resilience.

Summary

CVE-2025-4423 is a high-severity vulnerability identified in Insyde Software's InsydeH2O BIOS/UEFI firmware, specifically in a feature developed for Lenovo devices. The vulnerability is classified under CWE-119, which refers to improper restriction of operations within the bounds of a memory buffer, commonly known as a buffer overflow or out-of-bounds memory access issue. Such vulnerabilities typically allow an attacker to overwrite memory regions, potentially leading to arbitrary code execution, privilege escalation, or system crashes. The CVSS v3.1 score of 8.2 reflects a high impact, with the vector indicating local attack vector (AV:L), low attack complexity (AC:L), requiring high privileges (PR:H), no user interaction (UI:N), scope changed (S:C), and high impact on confidentiality, integrity, and availability (C:H/I:H/A:H). This means exploitation requires local access with elevated privileges but can result in complete compromise of the system's security state. Since the vulnerability resides in the BIOS/UEFI firmware layer, successful exploitation could allow attackers to execute code at a very low level, bypassing operating system security controls and persisting through OS reinstalls or disk replacements. No known exploits are currently reported in the wild, and no patches are linked yet, but Lenovo has been notified and maintains a security advisory page for updates. The vulnerability affects Lenovo devices using this specific InsydeH2O firmware feature, which suggests a limited but critical attack surface primarily targeting Lenovo hardware. The lack of user interaction and the scope change imply that once exploited, the attacker can affect system-wide security, potentially compromising all data and system functions.

CWE-119Improper Restriction of Operations within the Bounds of a Memory Buffer (opens in a new tab)
Class weaknessLikelihood of exploit: High
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
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.
Operation · Build and Compilation · Environment Hardening
Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index…
OWASP Cheat Sheets
XML Security (opens in a new tab)
Mass Assignment (opens in a new tab)
OWASP ASVS 4.0.3
V13.3.1 (opens in a new tab)
V5.1.4 (opens in a new tab)
V5.1.3 (opens in a new tab)
Attack patterns
Buffer Overflow via Environment Variables (opens in a new tab)
Overflow Buffers (opens in a new tab)
Client-side Injection-induced Buffer Overflow (opens in a new tab)
Filter Failure through Buffer Overflow (opens in a new tab)
MIME Conversion (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

Community reviews

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Exploitation evidence

What to do

Description

AI analysisMachine-generated, updated 15 Aug 2025, 00:47 UTC

WeaknessesCWE-119

Technical details

References

Community reviews

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