CVE-2026-20408: In wlan, there is a possible out of bounds write due to a heap buffer overflow

Q: How do I fix CVE-2026-20408?

software development kit: upgrade to newer than 7.6.7.2; openwrt: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Q: Is CVE-2026-20408 being exploited?

CVE-2026-20408 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2026-20408 affect?

CVE-2026-20408 affects software development kit, openwrt. Severity is high (CVSS 8.8). In wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploit

Routine

HIGH 8.8UPGRADEMITIGATE

CVE-2026-20408 is a high-severity flaw (CVSS 8.8) affecting software development kit, openwrt. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

In wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation. Patch ID: WCNCR00461651; Issue ID: MSV-4758.

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	8.8 (High)
Attack vector	Adjacent network
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.3% (top 78%)
CISA exploited list	No
Weakness	CWE-122, CWE-787
Published	2026-02-02
Last modified	2026-06-17

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

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-02-02 09:15 UTCPublished CVE record published
2026-06-17 10:17 UTCUpdated Record last modified

mediatek software development kit UPGRADE

Affected: <= 7.6.7.2

Fixed in: newer than 7.6.7.2

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy software-development-kit || rpm -q software-development-kit || software-development-kit --version

2. UPGRADE to newer than 7.6.7.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade software-development-kit

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade software-development-kit

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

openwrt openwrt MITIGATE

Affected: 19.07.0 · 21.02.0 · 23.05.0

Fixed in: no fixed release known

Safe to downgrade to: a release before 19.07.0

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-2026-20408?

software development kit: upgrade to newer than 7.6.7.2; openwrt: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20408 being exploited?

CVE-2026-20408 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-2026-20408 affect?

CVE-2026-20408 affects software development kit, openwrt. Severity is high (CVSS 8.8). In wlan, there is a possible out of bounds write due to a heap buffer overflow. This could lead to remote (proximal/adjacent) escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploit

How urgent is CVE-2026-20408?

Priority 36/100. High severity

Software pages

OpenWrt vulnerabilities

Related CVEs

CVE-2025-20742 HIGH 8.0 UPGRADE MITIGATE In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check
CVE-2025-20728 HIGH 7.8 DOWNGRADE In wlan STA driver, there is a possible out of bounds write due to an incorrect bounds check
CVE-2025-20733 HIGH 7.8 UPGRADE MITIGATE In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check
CVE-2025-20735 HIGH 7.8 UPGRADE MITIGATE In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check
CVE-2025-20737 HIGH 7.8 UPGRADE MITIGATE In wlan AP driver, there is a possible out of bounds write due to an incorrect bounds check

References

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