CVE-2026-20555 in MT2716
Summary
by MITRE • 11/02/2026
In Modem, there is a possible out of bounds read due to a missing bounds check. This could lead to remote denial of service, 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: MOLY01876664; Issue ID: MSV-9834.
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Analysis
by VulDB Data Team • 11/02/2026
The vulnerability identified in Modem firmware represents a critical security flaw characterized by an out-of-bounds read condition resulting from insufficient input validation and missing bounds checking mechanisms. This technical deficiency allows the system to access memory locations beyond the intended boundaries of allocated buffers, which can expose sensitive internal data or cause unpredictable behavior depending on the contents of adjacent memory regions. The root cause lies in the failure of the modem software to verify that incoming data structures conform to expected size constraints before processing them, a fundamental oversight in secure coding practices for embedded systems handling network protocols.
From an operational perspective, this vulnerability poses a severe risk of remote denial of service against user equipment connected to compromised cellular infrastructure. An attacker controlling a rogue base station can craft malicious signaling messages or protocol packets that trigger the out-of-bounds read condition within the modem's processing logic. Because the exploitation requires no additional execution privileges on the target device and does not necessitate any interaction from the end-user, the attack surface is significantly expanded. The victim simply needs to be in range of the rogue base station and have their device attempt to register or communicate with it for the vulnerability to be triggered.
The impact of this flaw extends beyond simple service disruption. While the primary reported consequence is denial of service, out-of-bounds reads can potentially lead to information disclosure if the accessed memory contains sensitive keys, configuration data, or other proprietary information stored in adjacent buffers. Furthermore, such memory corruption issues often serve as precursors to more severe exploits, including arbitrary code execution, although the current assessment highlights the reliability and ease with which service availability can be compromised. The lack of user interaction makes this particularly dangerous in scenarios involving automated device connections or background network scanning activities common in modern IoT deployments.
This vulnerability aligns closely with CWE-125, Out-of-bounds Read, as it involves accessing memory outside the bounds of a buffer due to unchecked input indices or lengths. In terms of attack tactics, it corresponds to MITRE ATT&CK techniques related to Denial of Service and potentially Initial Access through exploitation of remote services without user interaction. The specific context of cellular network protocols places this within the realm of radio interface layer attacks, where integrity checks are often bypassed by attackers leveraging specialized hardware or software-defined radios to simulate base station behavior.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Applying the provided patch ID MOLY01876664 is essential for resolving the specific instance of this flaw in affected modem firmware versions. Beyond patching, developers should implement rigorous bounds checking routines at all entry points where external data interacts with internal buffers. Utilizing static analysis tools and fuzz testing during the development lifecycle can help identify similar vulnerabilities before deployment. Additionally, network operators should consider deploying detection mechanisms for rogue base stations to mitigate the risk of exploitation in real-world scenarios by identifying anomalous signaling patterns associated with such attacks.