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GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable…

Info
CVECVE-2026-56389
First seen2026-07-29 12:15 UTC
Disclosed2026-07-29 11:16 UTC
Last updated2026-07-29 12:15 UTC
Channel statusauto

Summary

GNU Bison allows for an execution of an arbitrary program during HTML report generation due to improper handling of grammar-defined configuration variables. A grammar file can override the executable used for the XML‑to‑HTML transformation step via %define tool.xsltproc, which is accepted without restriction and passed directly to execvp(). When running bison --html on a attacker-provided grammar, this behavior allows execution of an arbitrary program with the privileges of the Bison process.…

In-depth triage · Auto channel

No in-depth report has been generated yet (DR-003 v2 AI pipeline is under construction).

Lint boundary warnings (3)

The following non-blocking warnings were raised during the lint phase of this triage (e.g. reference URLs not yet on the allowlist). They do not affect entry usability and are disclosed for transparency (see DR-002).

  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://cert.pl/en/posts/2026/07/CVE-2026-56389
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://cgit.git.savannah.gnu.org/cgit/bison.git/
  • REF_URL_NOT_ALLOWLISTED url not in allowlist: https://cgit.git.savannah.gnu.org/cgit/bison.git/commit/?id=3169c1e7a2c6acc4c59dfcf8b089896d6881925b

Sources

  • NVD DATABASE

Original Links

Timeline

  1. nvd_ingest NVD