CVE-2026-20526: In Modem, there is a possible out of bounds write due to a missing bounds check

Routine

HIGH 7.5MITIGATEMITIGATEMITIGATE

CVE-2026-20526 is a high-severity flaw (CVSS 7.5) affecting mt2716 firmware, mt2735 firmware, mt2737 firmware. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privileges needed. User interaction is needed for exploitation. Patch ID: MOLY01898195; Issue ID: MSV-8906.

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.5 (High)
Attack vector	Adjacent network
Attack complexity	High
Privileges needed	None
User interaction	None
EPSS exploit chance	0.2% (top 87%)
CISA exploited list	No
Weakness	CWE-787
Published	2026-10-05
Last modified	2026-10-08

Publisher (CNA): MediaTek, Inc. · Vendor: mediatek

Last updated 2026-10-08 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-10-05 02:16 UTCPublished CVE record published
2026-10-08 15:22 UTCUpdated Record last modified

mediatek mt2716 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mediatek mt2735 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mediatek mt2737 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mediatek mt6813 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mediatek mt6815 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

mediatek mt6833 firmware MITIGATE

Affected: all versions

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-20526?

mt2716 firmware: mitigate or apply the listed mitigation; mt2735 firmware: mitigate or apply the listed mitigation; mt2737 firmware: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20526 being exploited?

CVE-2026-20526 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-20526 affect?

CVE-2026-20526 affects mt2716 firmware, mt2735 firmware, mt2737 firmware. Severity is high (CVSS 7.5). In Modem, there is a possible out of bounds write due to a missing bounds check. This could lead to remote escalation of privilege, if a UE has connected to a rogue base station controlled by the attacker, with no additional execution privi

How urgent is CVE-2026-20526?

Priority 30/100. High severity

Related CVEs

CVE-2026-20540 MEDIUM 5.3 MITIGATE MITIGATE In Modem, there is a possible out of bounds read due to a missing bounds check
CVE-2026-20539 MEDIUM 5.3 MITIGATE MITIGATE In Modem, there is a possible out of bounds read due to a missing bounds check
CVE-2026-20538 MEDIUM 5.3 MITIGATE MITIGATE In Modem, there is a possible out of bounds read due to a missing permission check
CVE-2026-20534 MEDIUM 5.3 MITIGATE MITIGATE In Modem, there is a possible out of bounds read due to an incorrect bounds check
CVE-2026-20525 MEDIUM 5.3 MITIGATE MITIGATE In Modem, there is a possible system crash due to improper input validation

References

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