CVE-2026-49919 in Android
Summary
by MITRE • 09/08/2026
In tt_face_colr_blend_layer of ttcolr.c, there is a possible remote code execution due to an integer overflow. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/09/2026
The vulnerability identified within the FreeType library's handling of OpenType Color (COLR) font tables, specifically in the tt_face_colr_blend_layer function located in ttcolr.c, represents a critical security flaw rooted in improper integer arithmetic during the processing of complex glyph data. This issue manifests as an integer overflow that occurs when calculating memory offsets or buffer sizes based on user-supplied font metrics and layer indices. The root cause lies in the failure to validate whether intermediate calculations involving array bounds, blend factors, or coordinate transformations exceed the limits of a signed 32-bit integer before being used for memory allocation or pointer arithmetic operations. In modern computing environments where large fonts with extensive color layers are common, such as those found in web browsers and document viewers, this flaw allows an attacker to craft a malicious font file that triggers these erroneous calculations during routine rendering processes.
From a technical perspective, the integer overflow typically results in a wraparound effect where a positive value intended for memory allocation or indexing is interpreted as a negative number or a significantly smaller positive number due to bit truncation. This discrepancy leads to two primary failure modes: either an out-of-bounds write occurs if the system allocates insufficient memory based on the truncated size, allowing data to be written beyond the bounds of the allocated buffer into adjacent heap structures; or it results in an invalid pointer dereference that causes a crash, leading to denial of service. However, given the context of remote code execution potential, the more severe implication is the ability to corrupt heap metadata or overwrite critical function pointers within the application's memory space. By carefully crafting the malicious font file, an attacker can control the values involved in these calculations, thereby gaining precise control over where data is written and potentially achieving arbitrary write primitives that facilitate stack or heap exploitation techniques.
The operational impact of this vulnerability is severe due to its potential for remote code execution without user interaction. Since many applications automatically parse and render font files when displaying web content, opening documents, or processing image assets, an attacker can distribute a maliciously crafted COLR table within a website or document via phishing emails or compromised websites. When a victim views the content using a vulnerable version of FreeType-based software such as Firefox, Chrome, LibreOffice, or various PDF readers, the vulnerability is triggered automatically during the font parsing phase. This lack of required user interaction significantly lowers the barrier to exploitation for attackers and increases the likelihood of successful compromise in automated scanning scenarios or targeted attacks where social engineering elements are minimized.
In terms of privilege escalation, while the initial execution occurs within the context of the application process, which typically runs with standard user privileges, the ability to execute arbitrary code allows an attacker to leverage other local vulnerabilities for kernel-level access or exploit weaknesses in setuid binaries if present on the system. Furthermore, successful exploitation can lead to data exfiltration, installation of malware, and complete compromise of the host machine's confidentiality and integrity. The absence of additional execution privileges needed highlights the potency of this flaw as a standalone entry point into an otherwise secure environment, making it particularly dangerous in enterprise settings where endpoint protection may rely on detecting suspicious process behavior rather than preventing initial access through input validation failures.
To mitigate this risk, organizations must ensure that all software components utilizing FreeType are updated to versions that include patches for this integer overflow vulnerability. Developers should implement strict bounds checking and use safe arithmetic functions that detect overflows before performing memory operations. Specifically, validating that calculated indices do not exceed the maximum allowable size of arrays and ensuring that blend layer parameters fall within expected ranges can prevent the trigger conditions from being met. Additionally, deploying runtime application self-protection mechanisms or sandboxing techniques for applications handling untrusted font data can limit the blast radius if an exploit attempt occurs. Security teams should also monitor for anomalous memory access patterns associated with font rendering processes and consider disabling COLR table support in environments where high-fidelity color fonts are not strictly necessary, thereby reducing the attack surface entirely until comprehensive patches are deployed across all affected systems.