CVE-2026-20446 — Out-of-bounds Write in Mediatek MediaTek chipset
In sec boot, there is a possible out of bounds write due to an integer overflow. This could lead to local denial of service, if an attacker has physical access to the device, with User execution privileges needed. User interaction is not needed for exploitation. Patch ID: ALPS09963054; Issue ID: MSV-3899.
Who exploits it and how urgent it is
A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.
How the score was calculated
- EPSS 0.2% (30-day exploitation probability)+1
- Technical severity (medium)+3
The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).
Triage
Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.
CISA SSVC assessment CISA
Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.
Remediation
Fixes and mitigations documented by the sources — linked to the original advisory.
No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.
First 24 hours
Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.
- Identify exposed assets running the affected vendor/product/version combinations (Mediatek MediaTek chipset, Mediatek Mt6813 Firmware).
- No fix documented in the sources: reduce exposure and monitor the vendor advisory.
- Search available logs for exploit probes matching the vulnerability class (memory corruption), errors and authentication anomalies.
Affected scope
Vendor, product and versions as the sources word them.
| Vendor | Product | Versions | Status | Source |
|---|---|---|---|---|
| Mediatek | MediaTek chipset | version MT6813 | Vulnerable | CVE Program (cve.org) e CISA ADP |
| Mediatek | Mt6813 Firmware | versions not specified by the source | Vulnerable | NIST National Vulnerability Database |
Attack characteristics
The CVSS vector, decoded. It describes the attack, not your exposure to it.
Every base score collected
Sources score independently and may disagree; each row says who scored it and under which version.
| Score | Version | Severity | Expl. | Impact | Scored by |
|---|---|---|---|---|---|
| 4.3 | CVSS 3.1 | Medium | 0.7 | 3.6 | nvd@nist.gov via NIST National Vulnerability Database |
| 4.3 | CVSS 3.1 | Medium | 0.7 | 3.6 | 134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database |
| 4.3 | CVSS 3.1 | Medium | — | — | CISA-ADP via CVE Program (cve.org) e CISA ADP |
CVSS:3.1/AV:P/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H (score shown at the top: nvd@nist.gov) Weakness MITRE
Weakness class according to MITRE’s CWE catalog.
EPSS over time FIRST
Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.19%
Detection
Read off the CVSS vector and the weakness class. Starting points, not tested rules.
- Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
- Correlate service crashes/restarts with inbound traffic; repeated crashes may indicate attempts.
Timeline
What happened to this CVE, newest first.
- 2026
- Affected products added · mediatek, inc./mediatek chipset
- SSVC assessment updated
- Record published
- CVSS changed · 4.3
- Source status changed · → Analyzed
- Record created in this database
- CVE published
Source activity
Repeated readings are counted rather than listed.
- 1× Official description updated · Oct 13, 2026 – Oct 13, 2026
References
1 on the record
Elsewhere on this site
Related CVEs (same products)
- Medium CVE-2026-20589 Out-of-bounds Write in Mediatek Mt2718 Firmware 10d
- Medium CVE-2026-20588 Out-of-bounds Write in Mediatek Mt2718 Firmware 10d
- High CVE-2026-20586 Out-of-bounds Write in Mediatek Mt8910 Firmware 10d
- Medium CVE-2026-20541 In Modem, there is a possible out of bounds read due to a missing permission check. This… 10d
- Medium CVE-2026-20540 In Modem, there is a possible out of bounds read due to a missing bounds check. This… 10d
- Medium CVE-2026-20543 In Modem, there is a possible information disclosure due to a logic error. This could… 10d
Not in any source we poll
Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.
- No fixed version, patch or mitigation documented.
- No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
- No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
- No exploit packet captures, log samples, or incident case IDs supplied.
Answered from this record
Text assembled only from the fields above — no additional claims.
What should defenders know first?
CVE-2026-20446 is "Out-of-bounds Write in Mediatek MediaTek chipset", rated Medium. It affects MediaTek chipset (Mediatek); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 4.3 describes technical severity. EPSS 0.19% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.
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