# 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.

- **Severity:** High 8.7 (`CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 12 Aug 2026
- **Updated:** 13 Aug 2026
- **Also known as:** GHSA-gm3r-q2wp-hw87

## 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.

Weakness: CWE-407 (Inefficient Algorithmic Complexity), CWE-400 (Uncontrolled Resource Consumption)

## Which versions are affected by CVE-2026-73413?

4 open source packages ship an affected version, including shescape.


| Package | Ecosystem | 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.

## Is CVE-2026-73413 being exploited?

There is no known exploitation of CVE-2026-73413 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73413 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-73413 in the wild and no public exploit code.

Affected packages and fixed versions:
- shescape (npm): affected from 2.1.11; fixed in 2.1.14
- shescape (npm): affected from 2.1.11; fixed in 2.1.14
- shescape (npm): affected from 3.0.0; fixed in 3.0.1
- shescape (npm): affected from 3.0.0; fixed in 3.0.1

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-73413/ (Markdown: https://insights.sbomify.com/CVE-2026-73413/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73413
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73413
- OSV: https://osv.dev/vulnerability/CVE-2026-73413

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73413/
Summaries are generated and may contain mistakes; the official description above is the record.