Summary
membranemp4plugin has an unauthenticated denial-of-service via BEAM atom table exhaustion
membrane_mp4_plugin interns every 4-byte MP4 box name as a BEAM atom while parsing container headers, with no validation against an allow-list. Any code path that calls Membrane.MP4.Container.parse/1 (or the bang variant) on attacker-controlled MP4 bytes can be made to exhaust the BEAM atom table, which is uncapped at the source but bounded by the runtime ceiling (around 1,048,576 atoms) and never garbage-collected. Once the ceiling is hit, the entire BEAM node aborts.
Details
The MP4 container parser walks the input stream box-by-box. For each box, Membrane.MP4.Container.Header.parse/1 in lib/membrane_mp4/container/header.ex extracts the 4-byte name field and delegates to the private helper parse_box_name/1, which trims trailing spaces and passes the bytes through String.to_atom/1. Because String.to_atom/1 creates a new atom unconditionally, every distinct attacker-chosen 4-byte sequence becomes a permanent allocation in the global atom table. Atoms are not subject to garbage collection, so unique names accumulate for the lifetime of the node.
The fix replaces the unsafe interning with String.to_existing_atom/1 and treats unknown names as the :unknown atom downstream (with related plumbing in parse_helper.ex, serialize_helper.ex, and the ISOM/CMAF demuxer engines so the new error variant flows through cleanly).
PoC
- Generate an MP4-shaped payload of roughly 1.1 million minimal box headers, each 8 bytes long (4-byte size of 8, followed by a unique 4-byte ASCII name produced by enumerating combinations in the printable range).
- Concatenate them into a single binary (~8 MB total).
- Call
Membrane.MP4.Container.parse!/1on the binary inside any process running under the target BEAM node. - The node aborts once the atom table ceiling is reached.
References
Impact
An attacker who can get a single crafted MP4 file in front of any system that demuxes user-supplied media with membrane_mp4_plugin can crash the entire BEAM node hosting that pipeline, taking down every Erlang/Elixir application sharing the runtime. No authentication, network position, or user interaction is required beyond delivering the file to whatever processing path eventually calls the parser.
The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap. Typical impact: resource exhaustion leading to denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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Frequently Asked Questions
- What is CVE-2026-53423? CVE-2026-53423 is a medium-severity allocation of resources without limits or throttling vulnerability in membrane_mp4_plugin (erlang), affecting versions < 0.36.7. It is fixed in 0.36.7. The application allocates resources such as memory, threads, or file descriptors based on untrusted input without enforcing a cap.
- Which versions of membrane_mp4_plugin are affected by CVE-2026-53423? membrane_mp4_plugin (erlang) versions < 0.36.7 is affected.
- Is there a fix for CVE-2026-53423? Yes. CVE-2026-53423 is fixed in 0.36.7. Upgrade to this version or later.
- Is CVE-2026-53423 exploitable, and should I be worried? Whether CVE-2026-53423 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-53423 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-53423? Upgrade
membrane_mp4_pluginto 0.36.7 or later.