node-re2: String.prototype.replace(re2, template) aborts the Node process (uncatchable ToLocalChecked on empty MaybeLocal) when the result exceeds V8's max string length

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

6.2 · CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-71430: 0.16% estimated exploitation activity in the next 30 days; percentile 4.91 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

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): 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…

Published by the source

6 Aug 2026, 21:19 UTC

Last modified by the source

6 Aug 2026, 21:19 UTC

Source last checked

26 Oct 2026, 13:00 UTC

1. Revision 1 · created · 26 Oct 2026

   Published from ghsa record GHSA-8hcv-x26h-mcgp

Preview the exact text before you copy it. Commands are read-only suggestions; review them before running anything.

# Patch Next advisory brief: CVE-2026-71430

Advisory: node-re2: String.prototype.replace(re2, template) aborts the Node process (uncatchable ToLocalChecked on empty MaybeLocal) when the result exceeds V8's max string length
IDs: CVE-2026-71430, GHSA-8hcv-x26h-mcgp
Record: https://patchnext.com/advisories/cve-2026-71430 (revision 1, source checked 26 Oct 2026, 13:00 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: Medium (CVSS 6.2)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: re2 1.25.1. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm re2: affected <= 1.25.0; fixed in 1.25.1

## Suggested inspection (read-only)
- `npm ls re2 --all`: lists every installed copy and version, including transitive ones. Run in the project root after `npm ci`.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on re2.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://github.com/advisories/GHSA-8hcv-x26h-mcgp (GitHub-reviewed advisory GHSA-8hcv-x26h-mcgp lists affected ranges: npm re2 >=0 <=1.25.0)

Commands are suggestions: review each one before running it.