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Compiling Was a Bad Score for Vulnerability Repair

Harness artifacts and compiler flags moved the metric without proving a security fix.

Published Updated Story ID: mp-2026-09-23-004
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Summary

Harness artifacts and compiler flags moved the metric without proving a security fix.

A study of 203 vulnerable C and C++ functions found compile rate to be an unreliable proxy for LLM vulnerability repair. About 64% of compile failures were not attributed to the model, and a compiler-standard flag changed compile rates by 1.8 to 2.7 times on identical patches. A compiler-feedback loop also rewarded deletions and placeholders while similarity to human fixes fell. The authors propose a change-aware screen as a cheap filter, not a substitute for execution-grounded security evaluation.

Why it matters

Harness artifacts and compiler flags moved the metric without proving a security fix.

Limits and context

  • About 64% of compile failures were not attributed to the model, and a compiler-standard flag changed compile rates by 1.8 to 2.7 times on identical patches.
  • The authors propose a change-aware screen as a cheap filter, not a substitute for execution-grounded security evaluation.

Key claims

  1. Harness artifacts and compiler flags moved the metric without proving a security fix.

    Qualification: About 64% of compile failures were not attributed to the model, and a compiler-standard flag changed compile rates by 1.8 to 2.7 times on identical patches.

    Evidence: source-2026-09-23-004

Sources

  1. arXiv preprint 2609.26749arXiv · primary research

Corrections

No corrections have been recorded for this story.