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Microsoft AI scanner finds Rust library bugs reachable from safe code

2 sources · 2 articlesFirst reported Updated ()
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First merged summary.

Merged summary · x-ai/grok-4.7 · rewritten as coverage arrivesSummaries by Vani AI

Microsoft’s FORGE Lab reported standard-library soundness bugs that can let safe Rust trigger undefined behavior; two issues stayed open and practical exploitation looks unlikely.

Microsoft’s FORGE Lab said Hyenas, a research version of codename MDASH, found memory-safety bugs in Rust’s std and core libraries, including cases where entirely safe Rust can trigger undefined behavior. The issues are standard-library soundness bugs, not compiler miscompilations, grouped into three patterns of misplaced trust. According to CSO, a process::exit flaw present for nearly 11 years can, when called from a child thread, remove the main thread’s alternate signal stack, and CommandExt::exec can leave a pointer to freed memory. Microsoft said each flaw needs unusual conditions and found no reliable exploitation path for the signal-stack bug. Two reported issues remained open; the lab said maintainers triaged reports quickly, while CSO said Rust had not commented.

Key facts
  • Hyenas is FORGE Lab’s research version of codename MDASH.
  • process::exit flaw on stable Rust went undetected nearly 11 years.
  • Child-thread exit can turn a later stack overflow into a segmentation fault.
  • CommandExt::exec may leave an environment pointer referencing freed memory.
  • MapWindows::clone is issue 156501; a fix was reported, CSO said.
  • Two issues remained open; an execve-based fix was under review.
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Timeline

dated events in the reporting · oldest first
  1. Nov 9, 2026Microsoft published FORGE Lab findings on Rust library bugs · Microsoft Security Blog
  2. Nov 10, 2026CSO detailed stable Rust flaws and open issues · CSO Online

What each outlet adds

beyond the shared facts
  • Microsoft Security BlogThree misplaced-trust patterns and MapWindows::clone issue 156501.
  • CSO OnlineEleven-year process::exit flaw, freed-memory exec bug, exploitation unlikely.
Vendors
Rust project
Products
RustRust standard library
Organizations
MicrosoftFORGE Lab

Coverage

oldest first · one row per article · UTC
  1. · 2d ago Microsoft Security BlogFirst report

    Microsoft FORGE Lab finds memory-safety bugs in Rust’s standard library

    Some bugs let entirely safe Rust trigger undefined behavior; two reported issues were still open at publication.

  2. · 1d ago CSO Online

    Microsoft AI scanner finds long-lived Rust standard library bugs

    Two issues affect stable Rust, including a possible freed-memory access; Microsoft calls practical exploitation unlikely.