Security readout for executives and security teams
Plain-English summary
CVE-2026-20404 affects MediaTek modem chipsets. A nearby attacker operating a rogue base station could cause a connected device to crash. The impact described is denial of service, not data theft or code execution. Business urgency is highest for fleets using affected MediaTek-based phones, tablets, IoT, or automotive devices in exposed radio environments.
Executive priority
Treat as a medium-priority availability risk. Escalate for mission-critical mobile, IoT, or vehicle deployments where cellular disruption has operational impact. Patch through normal firmware channels, but prioritize exposed or hard-to-recover fleets.
Technical view
MediaTek describes improper input validation in Modem leading to possible system crash. CVSS 3.1 is 6.5, AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H. Exploitation requires the UE to connect to an attacker-controlled rogue base station. Patch ID is MOLY01689248; Issue ID is MSV-4837.
Likely exposure
Exposure depends on whether devices contain the listed MediaTek chipsets and receive modem firmware through OEM or carrier updates. The attack is proximity/radio-adjacent, not internet-routable. Default status is listed as unaffected except for the named chipset versions.
Exploitation context
No KEV listing or cited source indicates active exploitation. The attacker must control a rogue base station and have the target UE connect to it. No user interaction or device privileges are required once that condition is met.
Researcher notes
The public record gives limited technical detail. It identifies improper input validation and CWE-787, but does not publish packet formats, root cause specifics, or exploit evidence. Analysis should focus on affected chipset confirmation, patch provenance, and OEM firmware delivery status.
Mitigation direction
- Identify devices using the listed MediaTek chipsets.
- Check MediaTek February 2026 bulletin and OEM advisories for firmware availability.
- Prioritize modem/baseband firmware updates for affected devices.
- Coordinate with carriers or device vendors where updates are carrier-controlled.
- For high-risk deployments, reduce exposure to untrusted cellular environments where feasible.
Validation and detection
- Inventory device models and map them to MediaTek chipset identifiers.
- Confirm whether installed firmware includes patch ID MOLY01689248.
- Review OEM security bulletins for CVE-2026-20404 coverage.
- Verify carrier-managed devices have received the relevant modem update.
- Track unresolved affected models in vulnerability management tooling.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
CWE-787: Exact CWE lookup
Use the exact CWE identifier as the starting point before reviewing related ATT&CK behavior. Open the exact CWE lookup page first, then review the ATT&CK searches from that MITRE weakness context. This is a Glexia lookup hint, not an official ATT&CK mapping.
Open ATT&CK lookupCVE-2026-20404 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Medium
- CVSS
- 6.5 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H2.83.6Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
6.5MediumVector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Source materials
- CVE List V5 sourceCVE List V5
- https://corp.mediatek.com/product-security-bulletin/February-2026CVE reference
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.
Out-of-bounds Write
Out-of-bounds Write represents a recurring weakness pattern that can create exploitable paths when design, validation, or implementation controls are missing.