CVE-2026-111105 in rlottie
Summary
by MITRE • 10/15/2026
Telegram rlottie Numeric Truncation Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of Telegram. User interaction is required to exploit this vulnerability in that the target must visit a malicious page or open a malicious file.
The specific flaw exists within the rlottie library. The issue results from the lack of proper validation of user-supplied data, which can result in a write before the start of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-30207.
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Analysis
by VulDB Data Team • 10/15/2026
The identified security flaw resides within the rlottie library utilized by Telegram, representing a critical numeric truncation vulnerability that facilitates remote code execution. This specific issue is categorized under CWE-190 Integer Truncation and often leads to CWE-189 Integer Overflow or CWE-787 Out-of-bounds Write depending on the exact arithmetic operation involved in the processing of user-supplied data. The root cause stems from insufficient validation mechanisms when handling input parameters, specifically where large integer values are cast into smaller data types without proper bounds checking. This logical error allows an attacker to manipulate internal variables such as buffer sizes or array indices, resulting in a write-before-start condition where memory addresses preceding the allocated heap or stack region are overwritten. Such out-of-bounds writes corrupt adjacent memory structures, potentially overwriting function pointers, return addresses, or object metadata, which serves as the primary vector for achieving arbitrary code execution within the context of the currently running process.
From an operational perspective, this vulnerability requires user interaction to be successfully exploited, aligning with ATT&CK technique T1204 User Execution. The target must either visit a maliciously crafted webpage that triggers the vulnerable rendering path or open a specially constructed file containing malformed lottie animation data. Once triggered, the application processes the untrusted input through the rlottie engine without adequate sanitization of numeric fields related to layer dimensions, frame counts, or property values. By carefully crafting these inputs to induce integer truncation during size calculations, an attacker can cause the library to allocate a buffer smaller than expected while simultaneously writing data beyond its boundaries. This discrepancy enables the injection and execution of shellcode or other malicious payloads, effectively granting the adversary full control over the application's memory space and potentially leading to complete system compromise if privilege escalation vectors are present in the surrounding environment.
Mitigation strategies for this vulnerability involve both immediate patching and long-term architectural improvements within the Telegram client and its underlying dependencies. The primary remediation is to apply vendor-provided updates that address ZDI-CAN-30207 by implementing strict input validation routines specifically designed to detect integer truncation scenarios before they propagate into memory allocation functions. Developers should enforce type safety checks, ensuring that values intended for buffer sizing are validated against maximum allowable limits derived from system constraints rather than relying on implicit casting behaviors. Additionally, employing compiler-based protections such as stack canaries, Address Space Layout Randomization (ASLR), and Data Execution Prevention (DEP) can significantly reduce the likelihood of successful exploitation by making memory layout unpredictable and preventing execution of injected code in writable memory regions. For end-users, maintaining up-to-date software versions is critical to closing this attack surface, while security teams should monitor for indicators of compromise associated with malicious lottie files or suspicious network traffic patterns indicative of exploit attempts targeting media rendering components.