VulnerabilityPublished 2 Feb 2026Updated 30 Mar 2026

CVE-2026-20405: MediaTek chipset · Reachable Assertion

Affects MediaTek chipsetSource CVE Database V5

Not known to be exploited · CVSS 6.5 Medium.

Data as of 26 Oct 2026, 10:12 UTC

CVSS 3.1 base score

6.5Medium

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

EPSS: 0.2% chance of exploitation in 30 days – higher than 15% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

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

Attack Vector: Adjacent
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: None
Integrity: None
Availability: High

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

Attack Vector: Adjacent: The vulnerable component is bound to the network stack, but the attack is limited at the protocol level to a logically adjacent topology. This can mean an attack must be launched from the same shared physical (e.g., Bluetooth or IEEE 802.11) or logical (e.g., local IP subnet) network, or from within a secure or otherwise limited administrative domain (e.g., MPLS, secure VPN to an administrative network zone).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: None: There is no loss of confidentiality within the impacted component.
Integrity: None: There is no loss of integrity within 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 2 Feb 2026
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

Affected software

Product	Affected	Fixed in
MediaTek, Inc.MediaTek chipset	Affected MT2735 – MT8893 50 affected builds	Fixed in–

AI-suggested

To mitigate CVE-2026-20405, organizations and device manufacturers should promptly apply the official patch MOLY01688495 provided by MediaTek. Mobile device vendors should coordinate firmware updates and distribute them to end-users as soon as possible. Network operators can implement detection and mitigation strategies against rogue base stations, such as enhanced base station authentication, anomaly detection systems, and user alerts for suspicious network behavior. Enterprises should educate users about the risks of connecting to untrusted networks and encourage the use of trusted carriers. For IoT deployments using affected chipsets, firmware updates should be prioritized and tested for stability. Additionally, monitoring device logs for modem crashes or unusual disconnections can help identify potential exploitation attempts. Network segmentation and limiting device exposure to untrusted radio environments can reduce attack surface. Finally, collaboration between telecom providers, device manufacturers, and security researchers is essential to monitor for emerging exploits and develop further protective measures.

Description

In Modem, there is a possible system crash due to a missing bounds check. This could lead to remote denial of service, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: MOLY01688495; Issue ID: MSV-4818.

Impact

The primary impact of CVE-2026-20405 is a remote denial of service on devices using affected MediaTek chipsets. This can disrupt mobile communications by crashing the modem firmware, potentially causing devices to lose network connectivity or require rebooting. For end-users, this results in service interruptions, degraded user experience, and possible loss of critical communications. For organizations, especially telecom operators, mobile device manufacturers, and enterprises relying on mobile connectivity, this vulnerability could lead to service outages, customer dissatisfaction, and increased support costs. In critical infrastructure or emergency services relying on mobile networks, such disruptions could have severe operational consequences. The ease of exploitation without authentication or user interaction increases the risk, particularly in environments where attackers can deploy rogue base stations, such as public spaces, urban areas, or targeted locations. However, since the vulnerability does not affect confidentiality or integrity, data theft or manipulation is not a concern here. The broad range of affected chipset models amplifies the potential scope of impact worldwide.

CWE-617Reachable Assertion (opens in a new tab)
Base weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Implementation
Make sensitive open/close operation non reachable by directly user-controlled data (e.g. open/close resources)
Implementation · Input Validation
Perform input validation on user data.
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

corp.mediatek.com/product-security-bulletin/February-2026 (opens in a new tab)

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Mar 2026, 19:31 UTC

WeaknessesCWE-617

Technical details

References

Community reviews

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