CVE-2026-53429— Unbounded native memory leak in mdex escaped-tag rendering enables unauthenticated denial of service

Unbounded native memory leak in mdex escaped-tag rendering enables unauthenticated denial of service

Missing Release of Memory after Effective Lifetime vulnerability in leandrocp mdex and mdex_native allows an attacker who controls a rendered document to cause a denial of service through unbounded native memory exhaustion. The native rendering code permanently leaks memory when rendering a document that contains escaped-tag nodes. The conversion of each %MDEx.EscapedTag{} node into its native representation (From<ExEscapedTag> for NodeValue in the Rust NIF) calls Box::leak on the caller-supplied literal string, which surrenders the backing allocation so that it lives for the entire lifetime of the operating system process and is never freed. Both the byte length of each literal and the number of escaped-tag nodes in a document are attacker-controlled, and there is no size cap, rate limit, or string interning on this path. Every render of a document containing escaped-tag nodes therefore leaks literal_size x node_count bytes that can never be reclaimed, and repeated renders accumulate without bound. Rendering reaches this path through the public MDEx.to_html/1 entry point and any other API that renders a supplied %MDEx.Document{}. Any application that uses mdex (or mdex_native directly) to render documents derived from user-supplied content is affected. Because the leaked memory is never reclaimed for the life of the BEAM process, an attacker can drive resident memory upward without limit until the node exhausts memory and crashes, taking down every process on it. The vulnerable native code originally shipped inside mdex (in native/comrak_nif/src/types/document.rs) and was later extracted into the separate mdex_native package (native/mdex_native_nif/src/types/document.rs), where it remains unpatched. This issue affects mdex from 0.11.0 before 0.12.3, and mdex_native from 0.1.0 before 0.2.3.

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在移除最后引用时对内存的释放不恰当(内存泄露)

Leandro Pereira MDExNative 资源管理错误漏洞

Leandro Pereira MDExNative是加拿大Leandro Pereira个人开发者开源的一个服务器支撑系统。 Leandro Pereira MDExNative存在资源管理错误漏洞，该漏洞源于有效生命周期后内存未释放问题，可能导致控制已渲染文档的攻击者通过无界本机内存耗尽造成拒绝服务。

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