CVE-2026-49919 Overview
CVE-2026-49919 is an integer overflow vulnerability [CWE-190] in the tt_face_colr_blend_layer function of ttcolr.c, a FreeType component used for parsing TrueType color font tables. The flaw enables local escalation of privilege and possible remote code execution without requiring additional execution privileges or user interaction. Google addressed the issue in the Android Security Bulletin for September 2026.
Critical Impact
A local attacker can exploit the integer overflow in TrueType COLR font parsing to escalate privileges on affected Android devices without user interaction.
Affected Products
- Android devices incorporating the vulnerable FreeType ttcolr.c component
- Applications processing TrueType COLR color font layers via the affected FreeType code path
- Systems bundled in the September 2026 Android Security Bulletin scope
Discovery Timeline
- 2026-09-08 - CVE-2026-49919 published to the National Vulnerability Database
- 2026-09-01 - Fix included in the Android Security Bulletin September 2026
- 2026-09-10 - Last updated in NVD database
Technical Details for CVE-2026-49919
Vulnerability Analysis
The vulnerability resides in tt_face_colr_blend_layer, a function that blends color glyph layers when rendering TrueType COLR (Color) fonts. An integer overflow occurs during arithmetic on layer or glyph parameters derived from font file data. The overflow produces an undersized allocation or incorrect boundary calculation, which subsequently leads to memory corruption during blending operations.
Because font parsing runs inside privileged rendering contexts, the corruption can be leveraged to execute code with elevated privileges. Exploitation requires no user interaction beyond causing the malicious font to be processed. The description references possible remote code execution paths, though the CVSS attack vector is local.
Root Cause
The root cause is unchecked integer arithmetic on values sourced from untrusted font tables. When multiplied or summed, these values exceed the range of the destination integer type, wrap around, and produce a value smaller than the caller expects. Downstream buffer sizing or index computations then operate on the wrapped value, resulting in out-of-bounds memory access during layer blending.
Attack Vector
An attacker crafts a malicious TrueType font containing manipulated COLR table entries and delivers it through any channel that triggers font parsing. Local applications, system services, or components that render attacker-supplied fonts invoke the vulnerable code path. Successful exploitation escalates privileges to the context of the process performing the font rendering.
No verified public proof-of-concept code is available. Refer to the Android Security Bulletin September 2026 for the patch reference and affected component details.
Detection Methods for CVE-2026-49919
Indicators of Compromise
- Unexpected crashes or SIGSEGV signals in processes that load TrueType fonts, particularly those referencing ttcolr.c frames in stack traces
- Delivery or side-loading of untrusted font files (.ttf, .otf) containing COLR tables from non-standard sources
- Anomalous privilege transitions originating from font-rendering services or media processing components
Detection Strategies
- Monitor Android device patch levels and flag devices below the September 2026 security patch level
- Inspect crash dumps and tombstones for signatures pointing to tt_face_colr_blend_layer or adjacent FreeType frames
- Deploy application allowlisting to restrict installation of untrusted apps that could deliver malicious fonts
Monitoring Recommendations
- Enable telemetry on system font loading events and unusual font parsing errors
- Correlate process crashes in graphics or text rendering services with subsequent privilege changes
- Track Mobile Device Management (MDM) compliance for the September 2026 Android security patch level across the fleet
How to Mitigate CVE-2026-49919
Immediate Actions Required
- Apply the September 2026 Android security patch level to all managed Android devices
- Prioritize patch rollout for devices used by high-value users and those exposed to untrusted content
- Restrict installation of applications from unknown sources through MDM policy enforcement
Patch Information
Google published the fix in the Android Security Bulletin September 2026. Devices at security patch level 2026-09-01 or later address CVE-2026-49919. Original equipment manufacturers (OEMs) integrate the fix into their vendor-specific patch releases; confirm the exact build with the device vendor.
Workarounds
- Block delivery of untrusted font files through email, messaging, and web gateways where feasible
- Disable or sandbox applications that render arbitrary user-supplied fonts until patched
- Enforce Play Protect and restrict sideloading to reduce exposure to malicious font-bearing applications
# Verify Android security patch level on a managed device
adb shell getprop ro.build.version.security_patch
# Expected output: 2026-09-01 or later
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.