CVE-2026-58710: Film Grain Decoder RCE Vulnerability

CVE-2026-58710 Overview

CVE-2026-58710 is an out-of-bounds write vulnerability in the DecodeFilmGrainParams function of film_grain_dec.cc. The flaw stems from a missing bounds check during film grain parameter decoding. An attacker can trigger memory corruption by supplying a crafted media stream, leading to remote code execution. Exploitation requires no user interaction and no additional execution privileges. The issue is tracked in the Android Security Bulletin for September 2026 and is classified under CWE-120: Buffer Copy without Checking Size of Input.

Critical Impact
Attackers can achieve remote code execution on affected devices by delivering malicious media content that triggers a heap or stack write past allocated bounds during video decoding.

Affected Products

Android platform components incorporating the film_grain_dec.cc decoder (per Android Security Bulletin September 2026)
Pixel devices covered by the September 2026 Pixel update bulletin
Downstream vendor builds shipping the affected AV1 film grain decoder

Discovery Timeline

2026-09-15 - CVE-2026-58710 published to NVD
2026-09-16 - Last updated in NVD database

Technical Details for CVE-2026-58710

Vulnerability Analysis

The defect resides in DecodeFilmGrainParams, a routine in film_grain_dec.cc that parses film grain synthesis parameters. Film grain metadata accompanies AV1 video streams and controls how synthetic grain is layered onto decoded frames. The function writes parameter values into a fixed-size destination buffer without validating attacker-controlled indices or counts. When a crafted stream advertises parameter counts beyond the buffer capacity, the decoder writes outside the allocated region. This corruption can overwrite adjacent heap metadata, function pointers, or return addresses within the media codec process.

Root Cause

The root cause is a missing bounds check on indexed writes into a parameter array during film grain header parsing. [CWE-120] classifies this pattern as an unchecked buffer copy. The decoder trusts length or index fields extracted from the bitstream and uses them directly as write offsets. Because the values are not clamped against the destination buffer size, an attacker controls both the offset and the data written.

Attack Vector

The vulnerability is reachable through any pathway that delivers media content to the affected decoder. This includes messaging attachments, browser-rendered video, and streamed content processed by the media framework. The CVSS vector indicates a network-based attack with low complexity and no user interaction required. Successful exploitation yields code execution within the media codec process context, which can serve as a foothold for further privilege escalation. Refer to the Android Security Bulletin September 2026 for platform-level details.

Detection Methods for CVE-2026-58710

Indicators of Compromise

Unexpected crashes or SIGSEGV signals originating from the media codec process during AV1 playback
Anomalous child processes spawned by media framework components after processing untrusted video
Outbound network connections initiated by media decoder processes immediately following media ingest

Detection Strategies

Monitor mobile device management (MDM) telemetry for devices running Android builds predating the September 2026 security patch level
Inspect crash dumps for faults in DecodeFilmGrainParams or adjacent film grain parsing symbols
Apply behavioral analytics to flag media processes performing filesystem, network, or IPC actions inconsistent with normal decoding

Monitoring Recommendations

Track Android security patch level compliance across the mobile fleet and alert on drift
Ingest device crash and tombstone data into a centralized log platform for correlation
Baseline media codec process behavior and alert on deviations such as unexpected syscalls or memory allocations

How to Mitigate CVE-2026-58710

Immediate Actions Required

Update affected Android and Pixel devices to the September 2026 security patch level or later
Restrict installation of applications from untrusted sources that may deliver malicious media
Advise users to avoid opening AV1 video content from unknown senders until patches are applied

Patch Information

Google addressed the vulnerability in the September 2026 Android and Pixel security bulletins. Device manufacturers integrate the fix through the corresponding security patch level. Consult the Android Security Bulletin September 2026 for the specific patch identifiers and affected components.

Workarounds

Disable automatic media preview in messaging applications where feasible
Enforce mobile threat defense policies that block execution of untrusted media handlers
Segment untrusted content processing to devices maintained at current patch levels

bash

# Verify current Android security patch level on a device
adb shell getprop ro.build.version.security_patch
# Expected output for patched devices: 2026-09-01 or later