In Modem, there is a possible out of bounds write due to a missing bounds check.
Affects MediaTek chipsets including MT6739 and MT6761 through the Modem subcomponent. CVSS scores it 7.5 (high), and no vendor severity or fix is listed in the checked facts.
Written by anthropic/claude-haiku-5.5 from the sources below. Verify against them.
- Exploited
- No known exploitation
- Fix
- No fix listed
- Who is exposed
- Not reported
Do first: Workaround: The checked facts list no workaround. Until a fix is published, the vendor's advisory is the place to look for any interim guidance.
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- Published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- A 0-100 score for how much a CVE matters across the industry: exploitation, exposure, how widely the software is used, severity and whether a fix exists.What do these mean? →
- 24/100 · provisional
- How many real-world setups can hit the bug, from the vendor's advisory and CISA data. It does not know your setup.What do these mean? →
- Unclear
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: yes
- Technical impact: total
Summary
The affected software is the modem firmware in certain mobile devices, which handles cellular network communication. An attacker operating a rogue base station could exploit a missing bounds check to write data outside its intended memory, potentially gaining elevated privileges on the device without user interaction.
Read the original description
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 not needed for exploitation. Patch ID: MOLY01857954; Issue ID: MSV-8247.
What to do
Workaround: The checked facts list no workaround. Until a fix is published, the vendor's advisory is the place to look for any interim guidance.
Timeline
- CISA SSVC assessment
Exploitation: none · Automatable: yes · Technical impact: total
- CVE published
- First seen by cve.now1 day
- Record last updated
Affected versions
- MediaTek, Inc. MediaTek chipset
MT2716, MT2735, MT2737, MT6739, MT6761, MT6762, MT6763, MT6765, MT6767, MT6768, MT6769, MT6771, MT6779, MT6781, MT6783, MT6785, MT6789, MT6813, MT6833, MT6835, MT6853, MT6855, MT6858, MT6873, MT6875, MT6877, MT6878, MT6879, MT6880, MT6881, and 52 more
Evidence 1
- Link
Corrections
None so far.
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Questions about CVE-2026-20499
What does this mean?
A missing bounds check in the Modem subcomponent allows an out-of-bounds write, meaning data can be written outside the memory area it is meant for (CWE-787).Source: mediatek.com
Am I affected, and how do I check?
The listed MediaTek chipsets are affected, including MT2716, MT2735, MT2737, MT6739, MT6761, and MT6762. To check, look up the chipset model of the device in its specification or the vendor's documentation.Source: mediatek.com
What should I do about it?
The checked facts name no fixed version, so no upgrade target is available. Check the MediaTek security bulletin for an updated release.Source: mediatek.com
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: cve.now feed data
What if there's no patch?
The checked facts list no workaround. Until a fix is published, the vendor's advisory is the place to look for any interim guidance.Source: mediatek.com