CVE-2026-73413 Shescape: Quadratic-time denial of service in flag-protection
An attacker can cause denial of service by supplying large inputs to the Shescape library, consuming excessive CPU resources due to quadratic time complexity in flag protection.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-73413?
CVE-2026-73413 is a high-severity denial of service vulnerability in ericcornelissen shescape, published on 12 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Shescape is a simple shell escape library for JavaScript. From 2.1.11 until 2.1.14 and 3.0.1, the flag-protection loop in compose in src/internal/compose.js repeatedly joins and slices flag fragments when flagProtection is enabled, which is the default, making processing quadratic in input size across the escape, escapeAll, quote, and quoteAll APIs. An attacker who can supply a large untrusted input containing many flag fragments can consume CPU and cause denial of service. This issue is fixed in versions 2.1.14 and 3.0.1.
Which versions are affected by CVE-2026-73413?
4 open source packages ship an affected version, including shescape.
| Package | Affected | Fixed in |
|---|---|---|
shescape npm | From 2.1.11 | 2.1.14 |
shescape npm | From 2.1.11 | 2.1.14 |
shescape npm | From 3.0.0 | 3.0.1 |
shescape npm | From 3.0.0 | 3.0.1 |
How do I fix CVE-2026-73413?
Upgrade shescape to a fixed version for your release line: 2.1.14 or 3.0.1.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-73413 being exploited?
There is no known exploitation of CVE-2026-73413 in the wild and no public exploit code.
Sources
Also known as GHSA-gm3r-q2wp-hw87.