CVE-2018-21232: re2c before 2.0 has uncontrolled recursion that causes stack consumption in find_fixed_tags.

Security readout for executives and security teams

CVE-2018-21232 is an availability weakness in re2c before version 2.0. The issue is uncontrolled recursion in find_fixed_tags, which can consume stack memory during processing. Business impact is mainly build or tooling disruption where vulnerable re2c is used on risky inputs. Exposure is most plausible in developer, CI, packaging, or build systems that run re2c before 2.0. Risk is higher if re2c processes third-party or untrusted grammar/input files. Systems that do not run re2c, or only process trusted inputs, appear less exposed. Treat this as a targeted tooling availability issue, not an emergency internet-facing exposure based on current evidence. Prioritize remediation where vulnerable re2c is used in CI, release engineering, or package-building paths that affect delivery reliability. Mitigation focus: Inventory re2c installations in developer, CI, and packaging environments.; Upgrade re2c to version 2.0 or later where present.; Restrict re2c processing to trusted source inputs only..

Prepared

Jun 5, 2026, 14:59 UTC (UTC+00:00)

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.