Pierluigi PaganiniNovember 01, 2026
SMS of Death lets attackers crash Android call services with a hidden, zero-click message, blocking phone calls, even emergency calls too.
A specially manipulated SMS message is enough to crash Android’s phone service, interrupt ongoing calls, and temporarily render the smartphone unusable. The attack requires no interaction from the victim and can even compromise the ability to contact emergency services.
The vulnerability, dubbed the SMS of Death, is bringing renewed attention to the security of the messaging system in Android smartphones. The issue, documented by independent researcher Mark Blaszczyk, allows a remote attacker to cause a disruption in phone service by sending a single, specially crafted WAP Push message.
WAP Push (Wireless Application Protocol Push) is a particular message transmitted over the mobile network, generally in the form of a binary SMS, which contains structured data and is processed automatically by the smartphone without requiring user intervention. Unlike a traditional SMS, it can carry notifications, links to Internet resources, and configurations for mobile services.
The most worrying aspect is the execution method. It’s a zero-click attack, in which the recipient doesn’t have to open the message, select a link, or authorize any action. The content is automatically processed by the operating system and can cause the process responsible for phone functionality to crash.
The vulnerability affects “WapPushOverSms“, an Android framework component located in the “frameworks/opt/telephony” path, responsible for interpreting and managing WAP Push messages received by the device.
The technical cause lies in the incorrect handling of a numeric value used during message interpretation. Specifically, the “decodeWapPdu()” function, the researcher explains, reads the length of the WSP header through a value encoded as “uintvar” , initially returned as a 64-bit number. The value is subsequently converted to a 32-bit integer without prior range checking. This operation can transform a seemingly valid number into a negative value, which is then used to determine the size of an array. The consequence of this is a “NegativeArraySizeException” exception, thrown when Android attempts to allocate a negative-sized array. The exception is not handled correctly in the processing path and causes the “com.android.phone” process, responsible for telephony functions, to terminate.
The researcher demonstrated that a five-byte WSP header can generate the value “-2147483648“, which is sufficient to trigger the issue. Therefore, it is not necessary to transmit particularly large amounts of content to cause the issue.
“A 5-byte uintvar of 88 80 80 80 00 decodes to 0x80000000. Cast to a signed 32-bit int, that is -2147483648. Allocating new byte[-2147483648] throws an uncaught NegativeArraySizeException on the telephony main thread, killing com.android.phone:” reads the analysis.
An invisible attack that also interrupts emergency calls
The message is transmitted as a data SMSisn’t displayed in the message inbox and doesn’t generate a user-recognizable notification. The sender’s number isn’t normally visible in the conversation, and when the device receives the message, Android automatically starts processing it. A crash in the phone process causes a temporary loss of connectivity and interrupts active voice calls, including those to emergency services
According to the researcher’s published evidence, each message processing can cause a disruption in telephone service lasting about one to two seconds, during which the component is rebooted. However, the problem can become much more serious if the message is processed repeatedly.
One of the most significant aspects of SMS of Death is the ability to transform a simple crash into a persistent Denial of Service condition. The malicious message can remain in the incoming SMS queue and be reprocessed during subsequent delivery attempts. The telephone operator’s retransmission mechanism can also contribute to a repeat of the event, causing further service disruptions.
The researcher reports observing intermittent crashes for up to a week after receiving a single message. Sending around twenty specially crafted messages can render the device unusable for an extended period. In more severe cases, the phone process can continue to crash during system startup, triggering a condition similar to a boot loop. Recovery may require using the Android Debug Bridge (ADB) on a computer, directly intervening in the queue of messages waiting to be processed. For a typical user, this is far from a simple procedure.
A threat to communications availability
SMS of Death demonstrates how a cyberattack doesn’t necessarily have to involve information theft, code execution, or device control to have significant consequences. In this case, the target is phone service availability, a crucial feature especially when contacting emergency services. The ability to interrupt communications without any user interaction makes this vulnerability particularly sensitive. To reduce exposure, it’s important to check the Android security patch level installed and apply available updates, paying particular attention to devices no longer receiving manufacturer support.
Testing conducted by Mark Blah has shown that the issue is reproducible on several devices, including the Google Pixel 9 and Samsung smartphones from the Galaxy and Galaxy A families. The vulnerable code appears to be present on Android versions ranging from Android 12 to Android 17. However, the availability of the fix is not uniform across all generations of the operating system.
According to documentation published by the researcher, Google has distributed a fix 17. Older devices, such as those running Android 12 and 13, may remain exposed if they do not receive corrective updates
About the author: Salvatore Lombardo (X @Slvlombardo)
Electronics engineer and Clusit member, for some time now, espousing the principle of conscious education, he has been writing for several online magazine on information security. He is also the author of the book “La Gestione della Cyber Security nella Pubblica Amministrazione”. “Education improves awareness” is his slogan.
Follow me on Twitter: @securityaffairs and Facebook and Mastodon
(SecurityAffairs – hacking, SMS of Death)
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