CVE-2026-20499 MediaTek, Inc. CVE debrief

Who should care

Defenders responsible for Modem and UE systems should assess exposure and prioritize patching. This includes reviewing the vendor bulletin for specific patching guidance, assessing the environment for potential exposure, and monitoring for signs of exploitation. Security teams and vulnerability management teams should also review the CVE record and vendor guidance for further details.

Why it matters

Defenders should prioritize verifying and applying patches from the vendor, assessing exposure in their environment, and monitoring for potential exploitation attempts.

• Remote escalation of privilege possible
• No additional execution privileges needed
• User interaction not required for exploitation
• Patch verification and application recommended

Technical summary

A possible out of bounds write due to a missing bounds check was identified in Modem. 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 not needed for exploitation. The issue, tracked as MSV-8247, was patched as part of MOLY01857954. The vulnerability affects Modem components and defenders should focus on verifying and applying patches from the vendor, assessing exposure, and monitoring for exploitation attempts.

Defensive priority

Defenders should prioritize verifying and applying patches from the vendor, assessing exposure in their environment, and monitoring for potential exploitation attempts.

Recommended defensive actions

• Verify and apply patches from the vendor
• Assess exposure in your environment
• Monitor for potential exploitation attempts
• Review compensating controls for exposed systems
• Check relevant monitoring, detection, and logs for exposed assets
• Track exceptions and retest remediated assets
• Confirm whether affected product deployments exist in managed environments

Evidence notes

The CVE record and vendor bulletin provide limited information about the vulnerability. Further verification and testing may be necessary to fully understand the impact and potential exploitation. The vendor has provided a patch, identified as MOLY01857954, and defenders should verify and apply this patch. The CVE record was published on 2026-11-02T03:17:31.090Z and has not been modified since then.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.