CVE-2026-77299
Dashboard / Vulnerabilities / CVE-2026-77299
Summary: Regexp2: Unbounded memory amplification via large `{m}` quantifier on a zero-width subexpression
Details: Regexp2 is a feature-rich RegExp engine for Go. Prior to version 2.3.0, when regexp2 compiles and matches a pattern containing a large fixed-count quantifier applied to a zero-width subexpression — e.g. (?:){50000000} — the match engine executes the empty loop body m-1 times, pushing two integers onto the backtracking stack on every iteration. Because the parser accepts any repetition count up to math.MaxInt32 and the backtracking stack grows without bound, a pattern of fewer than 20 bytes matched against an empty input can force multi-gigabyte allocation and OOM-kill the process. MatchTimeout does not fully mitigate this because the memory is allocated faster than the 100 ms timeout clock can fire. This issue has been patched in version 2.3.0.
References: https://github.com/dlclark/regexp2/releases/tag/v2.3.0, https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/77xxx/CVE-2026-77299.json, https://github.com/dlclark/regexp2/security/advisories/GHSA-wq9v-j77v-qr26, https://nvd.nist.gov/vuln/detail/CVE-2026-77299, https://github.com/dlclark/regexp2/commit/6e446cb3a57a0f20112bc24353604fd00bdb309a
Affected packages
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