CVE-2026-53428
Memory Allocation with Excessive Size Value vulnerability in leandrocp mdex allows an unauthenticated attacker to cause a denial of service through unbounded memory allocation.
Overview
CVE-2026-53428 is a known-severity vulnerability. It was published on June 29, 2026.
Technical description
Memory Allocation with Excessive Size Value vulnerability in leandrocp mdex allows an unauthenticated attacker to cause a denial of service through unbounded memory allocation.
comrak_nif::lumis_adapter::LumisAdapter::parse_highlight_lines in native/comrak_nif/src/lumis_adapter.rs eagerly expands a user-controlled inclusive line range from a fenced code block's highlight_lines decorator into a Vec<usize>, pushing one element per integer in the range with no upper bound on the range size. An attacker who can supply Markdown that an application renders with MDEx.to_html/2 (for example a comment, chat message, or wiki page) can embed a code block whose info string is rust highlight_lines="1-100000000", forcing the native adapter to allocate roughly 8 bytes per line in the range.
A payload that differs by only a few bytes can therefore allocate hundreds of megabytes, and a sufficiently large range (for example 1-2000000000) exhausts host memory and aborts the BEAM, denying service to eve
Remediation
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
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Frequently asked questions
What is CVE-2026-53428?
CVE-2026-53428 is a known-severity vulnerability. It was published on June 29, 2026.
How severe is CVE-2026-53428?
CVSS score information is not yet available for this vulnerability. Check back as the CVE record is updated by NVD analysts.
How do I fix or remediate CVE-2026-53428?
Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.
How can CyberStrike help with CVE-2026-53428?
CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-53428 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.