CVE-2026-58699 Overview
CVE-2026-58699 is an out-of-bounds read vulnerability in the Android VP9 hardware video decoder. The flaw resides in the Vp9DecEndOfStream function within vp9hwd_output.cc and stems from an incorrect bounds check. A local attacker can trigger the condition to achieve local escalation of privilege without requiring additional execution privileges. Exploitation does not require user interaction, which increases the risk on affected devices. The issue is tracked in the Android Security Bulletin for September 2026 and is classified under [CWE-125] (Out-of-Bounds Read).
Critical Impact
Local privilege escalation on affected Android devices through malformed VP9 stream processing, with no user interaction required.
Affected Products
- Android platform components processing VP9 video streams
- Pixel devices referenced in the September 2026 Android Security Bulletin
- Downstream Android distributions incorporating the affected vp9hwd_output.cc component
Discovery Timeline
- 2026-09-15 - CVE-2026-58699 published to the National Vulnerability Database
- 2026-09-17 - Last updated in the NVD database
Technical Details for CVE-2026-58699
Vulnerability Analysis
The vulnerability exists in the Vp9DecEndOfStream routine defined in vp9hwd_output.cc. The function performs an incorrect bounds check when finalizing output during VP9 stream termination. As a result, the decoder reads memory past the intended buffer boundary. The out-of-bounds read exposes adjacent memory contents to the decoder context. Combined with the elevated privileges of the media processing pipeline, this exposure enables local privilege escalation. The bug requires no user interaction, so any local process able to submit crafted VP9 input can trigger the condition.
Root Cause
The root cause is an incorrect bounds validation in the end-of-stream handling logic. The check fails to constrain the read offset against the actual output buffer size. This condition falls under [CWE-125], where a program reads data past the end or before the beginning of an intended buffer.
Attack Vector
The attack vector is local. An attacker must have code execution on the device, typically through an unprivileged application. The malicious process supplies a crafted VP9 bitstream to the hardware decoder, forcing execution of the flawed end-of-stream path. Leaked memory contents can then be used to bypass address space layout randomization or influence subsequent decoder state, escalating privileges within the media stack. See the Android Security Bulletin September 2026 for component-level details.
Detection Methods for CVE-2026-58699
Indicators of Compromise
- Unexpected crashes or SIGSEGV signals in the Android media codec service tied to VP9 decoding
- Anomalous VP9 media files delivered to devices from untrusted local applications
- Media server logs referencing Vp9DecEndOfStream failures or decoder reinitialization loops
Detection Strategies
- Monitor Android tombstones and logcat output for crashes originating in vp9hwd_output.cc
- Inspect installed applications for permissions to invoke hardware media codecs with attacker-controlled input
- Correlate decoder faults with process activity to identify applications repeatedly submitting malformed VP9 streams
Monitoring Recommendations
- Track Android patch level compliance across the fleet using mobile device management telemetry
- Alert on installation of applications requesting broad media or codec access from unverified sources
- Ingest device crash and security logs into a centralized analytics platform for behavioral baselining
How to Mitigate CVE-2026-58699
Immediate Actions Required
- Apply the September 2026 Android security patch level to all managed devices
- Restrict sideloading and enforce installation only from vetted application sources
- Audit installed applications for those interacting with hardware video decoders
Patch Information
The fix is delivered through the September 2026 Android Security Bulletin. Device manufacturers and carriers distribute the patch as part of the monthly security update. Administrators should confirm devices report the September 2026 or later security patch level. Reference the Android Security Bulletin September 2026 for build identifiers and component fixes.
Workarounds
- Block installation of untrusted applications through mobile device management policy until patches are deployed
- Prevent execution of media files from unknown sources on unpatched devices
- Isolate high-risk devices from processing untrusted VP9 content until the vendor update is applied
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
