CVE-2026-53426
Atom-table exhaustion denial-of-service via JSON parse_document in MDEx
Description
Allocation of Resources Without Limits or Throttling vulnerability in leandrocp MDEx allows Excessive Allocation. MDEx.parse_document/2 accepts a {:json, json} source. In lib/mdex.ex, the private json_to_node/1 function passes the attacker-controlled node_type value to Module.concat/1, which calls String.to_atom/1 and interns a brand-new atom for every distinct value. Atoms are never garbage collected on the BEAM, so a crafted JSON document carrying a unique node_type at each (deeply nested) node mints one permanent atom per node. A single document can intern hundreds of thousands of atoms, and a large enough document exhausts the default atom table (around 1,048,576 atoms) and aborts the entire Erlang VM, taking down every process on the node. Any application that passes untrusted input to the {:json, ...} source of MDEx.parse_document is exposed to an unauthenticated denial-of-service. This issue affects mdex from 0.4.3 before 0.13.2.
INFO
Published Date :
June 29, 2026, 8:17 p.m.
Last Modified :
June 30, 2026, 2:14 p.m.
Remotely Exploit :
No
Source :
6b3ad84c-e1a6-4bf7-a703-f496b71e49db
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db | ||||
| CVSS 4.0 | HIGH | 6b3ad84c-e1a6-4bf7-a703-f496b71e49db |
Solution
- Update MDEx to version 0.13.2 or later.
- Implement input validation for JSON documents.
- Consider rate limiting for JSON parsing requests.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-53426.
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-53426 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-53426
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-53426 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-53426 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 29, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-53426', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-29T20:49:38.921685Z'} -
New CVE Received by 6b3ad84c-e1a6-4bf7-a703-f496b71e49db
Jun. 29, 2026
Action Type Old Value New Value Added Affected [{'cpes': ['cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/leandrocp/mdex', 'vendor': 'leandrocp', 'modules': ["'Elixir.MDEx'"], 'product': 'mdex', 'versions': [{'status': 'affected', 'version': '0.4.3', 'lessThan': '0.13.2', 'versionType': 'semver'}], 'packageURL': 'pkg:hex/mdex', 'packageName': 'mdex', 'programFiles': ['lib/mdex.ex'], 'collectionURL': 'https://repo.hex.pm', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.MDEx':parse_document/2"}, {'name': "'Elixir.MDEx':json_to_node/1"}]}, {'cpes': ['cpe:2.3:a:leandrocp:mdex:*:*:*:*:*:*:*:*'], 'repo': 'https://github.com/leandrocp/mdex', 'vendor': 'leandrocp', 'modules': ["'Elixir.MDEx'"], 'product': 'mdex', 'versions': [{'status': 'affected', 'version': 'cbb59a3f792dbc343873adec3466f49c853dc309', 'lessThan': '00fddf444220a1f1cc0af0a1cab6738804878387', 'versionType': 'git'}], 'packageURL': 'pkg:github/leandrocp/mdex', 'packageName': 'leandrocp/mdex', 'programFiles': ['lib/mdex.ex'], 'collectionURL': 'https://github.com', 'defaultStatus': 'unaffected', 'programRoutines': [{'name': "'Elixir.MDEx':parse_document/2"}, {'name': "'Elixir.MDEx':json_to_node/1"}]}] Added Description Allocation of Resources Without Limits or Throttling vulnerability in leandrocp MDEx allows Excessive Allocation. MDEx.parse_document/2 accepts a {:json, json} source. In lib/mdex.ex, the private json_to_node/1 function passes the attacker-controlled node_type value to Module.concat/1, which calls String.to_atom/1 and interns a brand-new atom for every distinct value. Atoms are never garbage collected on the BEAM, so a crafted JSON document carrying a unique node_type at each (deeply nested) node mints one permanent atom per node. A single document can intern hundreds of thousands of atoms, and a large enough document exhausts the default atom table (around 1,048,576 atoms) and aborts the entire Erlang VM, taking down every process on the node. Any application that passes untrusted input to the {:json, ...} source of MDEx.parse_document is exposed to an unauthenticated denial-of-service. This issue affects mdex from 0.4.3 before 0.13.2. Added CVSS V4.0 AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:H/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X Added CWE CWE-770 Added Reference https://cna.erlef.org/cves/CVE-2026-53426.html Added Reference https://github.com/leandrocp/mdex/commit/00fddf444220a1f1cc0af0a1cab6738804878387 Added Reference https://github.com/leandrocp/mdex/security/advisories/GHSA-923r-7vf4-5vw8 Added Reference https://osv.dev/vulnerability/EEF-CVE-2026-53426