Vulnerability in re2 (CVE-2026-71430)
Summary
Vulnerability in re2 (CVE-2026-71430). Risk of unauthorized operations or information disclosure. Exploitable via MaybeLocal. Mitigation: upgrade to 1.25.1 or later.
Original description
The description as published by the source.
Description
WrappedRE2::Replace builds the replacement result and hands it to V8 with .ToLocalChecked() without checking for the empty MaybeLocal that V8 returns when the string/buffer exceeds its maximum length:
lib/replace.cc (v1.24.1):
// L553 — Buffer return path
info.GetReturnValue().Set(Nan::CopyBuffer(result.data(), result.size()).ToLocalChecked());
// L556 — String return path
info.GetReturnValue().Set(Nan::New(result).ToLocalChecked());
When a global replace uses an output-amplifying template — $' (text after the match) or $` (text before the match) — the result grows to O(input²). For an input of ~40,000+ identical single-char matches the result exceeds V8's String::kMaxLength (~536,870,888 chars on 64-bit). Nan::New(result) then returns an empty MaybeLocal, and the unchecked .ToLocalChecked() calls v8::Utils::ReportApiFailure → FATAL ERROR: v8::ToLocalChecked Empty MaybeLocal → abort() (SIGABRT).
This is an uncatchable crash: it is not a JavaScript exception, so a surrounding try/catch cannot stop it — the entire Node process (or worker) dies.
The built-in regex engine handles the identical case correctly by throwing a catchable RangeError: Invalid string length. node-re2 diverges from that contract and aborts instead.
Proof of concept
npm i re2
node poc.js
const RE2 = require('re2');
// Built-in engine: same case -> CATCHABLE RangeError (correct)
try { 'a'.repeat(50…
Source: GitHub Security Advisories (Global) NVD GitHub Advisory
Auto-generated summary
Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.
A vulnerability tracked as CVE-2026-71430 has been found in re2.
Attackers can target a specific entry point like MaybeLocal over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.2/10.
What to do: upgrade re2 to 1.25.1 or later.
If unsure, ask your IT team or search "re2 CVE-2026-71430" on the vendor's site.
CVE-2026-71430 (re2) — CWE-617 / CVSS v3 6.2
Attack vector: local / unauthenticated / no user interaction
Attack surface: MaybeLocal / String.prototype.replace / ToLocalChecked / RangeError
Patched: 1.25.1 — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
A vulnerability (CWE-617) exists in re2. Attackers reach the vulnerable code path via MaybeLocal without authentication.
Check the vendor advisory for the affected versions of re2. Attack surface: MaybeLocal / String.prototype.replace / ToLocalChecked / RangeError.
Severity: Medium (CVSS 6.2/10). Risk of unauthorized operations or information disclosure.
Update to 1.25.1.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 're2' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response actions
Concrete steps and command examples for SOC/SRE teams to execute in order
-
1Identify exposure identify
grep -r 're2' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で
re2を grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade re2 to 1.25.1ステージング環境で 1.25.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスを含めること。
-
3Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。
Affected packages
References
- package github.com
- web github.com
- web github.com