GStreamer H265 plugin: GStreamer H265 Codec Parsing Stack-based Buffer Overflow (CVE-2025-3887) #shorts

Summary

In May 2025, a critical remote code execution vulnerability was disclosed in GStreamer’s H265 codec parser. Tracked as CVE-2025-3887 (ZDI-CAN-26596), this stack-based buffer overflow allows a remote attacker to execute arbitrary code in the context of any application that uses the vulnerable library.

Product details

The issue affects GStreamer, an open-source multimedia framework widely used in Linux distributions and embedded devices. The vulnerable code resides in the H265 slice header parser, which is provided by the gstreamer-plugins-bad package. Fedora 41 and several SUSE releases have already published updates to address this fault.

Vulnerability type summary

CWE-121: Stack-based Buffer Overflow. The flaw occurs when untrusted data intended for H265 slice headers is copied into a fixed-size buffer on the stack without proper length validation, opening the door to memory corruption and control-flow hijacking.

Details of the vulnerability

When GStreamer processes a crafted H265 video stream, the parser reads slice header information and copies it into a stack buffer. Because the code does not verify that the user-supplied length fits within that buffer, an attacker-supplied header can overflow the stack. By carefully crafting the overflow, an attacker can overwrite return addresses or function pointers to redirect execution to malicious payloads. Successful exploitation requires only that the target application invokes the H265 parser, making any multimedia tool or service that links against the vulnerable GStreamer library a potential target.

Conclusion

CVE-2025-3887 represents a high-severity risk for any system handling H265 video content with GStreamer. Administrators and developers should immediately apply the Fedora 41 update or the SUSE security patches for gstreamer-plugins-bad. Users are also advised to review any custom builds of the library, upgrade to non-vulnerable versions, and monitor multimedia services for anomalous behavior.

Watch the full video on YouTube: CVE-2025-3887

Remediation and exploitation details

This chain involves the following actors

  • Remote Attacker: Crafts and delivers malicious H265 payload
  • System Administrator: Responsible for applying security updates

This following systems are involved

  • GStreamer H265 Plugin (Parses H265 video streams): Contains the vulnerable slice header parser
  • Media Application (Uses GStreamer to decode or stream video): Runs GStreamer in user context

Attack entry point

  • H265 Slice Header Parser: Copies user-supplied slice header data into a fixed-size stack buffer without length validation

Remediation actions

System Administrator
Install security updates
gstreamer and gstreamer-plugins-bad packages
System Administrator
Verify updated version
GStreamer H265 Plugin (commit ≥ patched version)
System Administrator
Restrict untrusted inputs
Media Application configuration

Exploitation actions

Stack-based buffer overflow in slice header copy

Remote Attacker
Prepare malicious H265 bitstream
GStreamer H265 Plugin
Examples:
  • Use a custom tool to generate an H265 stream where the slice header length field exceeds the expected buffer size
  • Embed shellcode or return-oriented-programming gadgets into the overflow region

Open or play the malicious video

Remote Attacker
Deliver the crafted H265 file or stream
Media Application
Examples:
  • Convince a user to open the file in a GStreamer-based player
  • Serve the stream via a networked video server that uses GStreamer

Parser copies oversized slice header into stack buffer

Remote Attacker
Trigger the overflow during parsing
GStreamer H265 Plugin
Examples:
  • Application calls gst_element_push_buffer on the oversized frame
  • Parser executes memcpy of attacker-controlled data past buffer boundary

Overwrite return address to jump to injected code

Remote Attacker
Hijack control flow and execute payload
GStreamer Process
Examples:
  • Overflow frame pointer and return address to point to shellcode
  • Use return-oriented programming to bypass non-executable stack protections

Related Content

NOTE: The following related content has not been vetted and may be unsafe.

CVE database technical details

CVE ID
CVE-2025-3887
Description
GStreamer H265 Codec Parsing Stack-based Buffer Overflow Remote Code Execution Vulnerability. This vulnerability allows remote attackers to execute arbitrary code on affected installations of GStreamer. Interaction with this library is required to exploit this vulnerability but attack vectors may vary depending on the implementation. The specific flaw exists within the parsing of H265 slice headers. The issue results from the lack of proper validation of the length of user-supplied data prior to copying it to a fixed-length stack-based buffer. An attacker can leverage this vulnerability to execute code in the context of the current process. Was ZDI-CAN-26596.
Provider
zdi
CWE / problem types
CWE-121: Stack-based Buffer Overflow
Affected Software Versions
GStreamer:GStreamer:[{'version': '2e8b542145c1b11f8b8d927f6c679fd8028ceb60', 'status': 'affected'}]
Date Published
2025-05-22T00:47:04.097Z
Last Updated
2025-05-22T18:39:26.850Z