Quick answers
- Is CVE-2026-53429 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-53429 being exploited in the wild.
- How severe is CVE-2026-53429?
- Informational severity, with a CVSS score of 6.9, published 29 June 2026.
- Which products and versions are affected?
- leandrocp mdex >= 0.11.0, < 0.12.3; leandrocp mdex_native >= 0.1.0, < 0.2.3.
- Is there a fix for CVE-2026-53429?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-53429 attacked?
- It is attacked with local access, in a software library.
- Am I affected by CVE-2026-53429?
- Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A Missing Release of Memory after Effective Lifetime (CWE-401) exists in the Rust NIF component of mdex and mdex_native. The vulnerability is located in the conversion of %MDEx.EscapedTag{} nodes into their native representation within document.rs, where the code calls Box::leak on caller-supplied literal strings. Because the byte length and frequency of these nodes are attacker-controlled and lack size limits or string interning, repeated rendering of malicious documents results in a permanent native memory leak. This eventually exhausts the memory of the BEAM process, leading to a crash. The issue is fixed in mdex 0.12.3 and mdex_native 0.2.3.
Affected products
- leandrocp mdex >= 0.11.0, < 0.12.3
- leandrocp mdex_native >= 0.1.0, < 0.2.3
Timeline
- 2026-06-29: advisory: GHSA-cmvp-gp9f-23xw published
- 2026-06-29: disclosed: CVE-2026-53429 published