How severe is CVE-2026-73413?

No CVSS score has been assigned to CVE-2026-73413 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-73413?

CVE-2026-73413 affects the following packages: shescape (npm), shescape (npm). Ecosystems affected: npm.

How do I fix CVE-2026-73413?

Update shescape to 2.1.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73413 is resolved across your whole dependency graph.

How do I detect CVE-2026-73413 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for shescape, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-73413 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2026-73413 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-73413 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-73413?

CVE-2026-73413 has an EPSS (Exploit Prediction Scoring System) score of 0.6%, placing it in the 46th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-73413?

CVE-2026-73413 is classified as Uncontrolled Resource Consumption (CWE-400), CWE-407 (CWE-407). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-73413 published, and has it been updated?

CVE-2026-73413 was published on August 12, 2026 and was last updated on September 11, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

Not in CISA KEV

CVE-2026-73413 — shescape

Fix: ericcornelissen/shescape@43d70b5

CVE-2026-73413 is a Uncontrolled Resource Consumption vulnerability in shescape. A fix is available for shescape — see the affected versions and patch details below.

Shescape: Quadratic-time denial of service in flag-protection

Also known asGHSA-gm3r-q2wp-hw87

Published

Aug 12, 2026

Updated

Sep 11, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Sep 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73413.

EPSS Exploitation Probability

via FIRST.org ↗

0.6%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs46th percentile — riskier than 46% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

25other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

shescapenpm

23Kdownloads / week

Description

Impact

This impacts users of Shescape that have flag protection enabled, which is on by default, regardless of the API being used.

An attacker can cause a runtime quadratic in the input size, causing denial of service for large inputs.

import { Shescape } from "shescape";

// 1. Prerequisites
const options = {
    //flagProtection unspecified
    // Or
    flagProtection: true,
};

// 2. Payload
let payload = "\u0000-".repeat(32000);

// 3. Usage
const shescape = new Shescape(options);
let callback;

callback = () => shescape.escape(payload);
// Or
callback = () => shescape.escapeAll([payload]);
// Or
callback = () => shescape.quote(payload);
// Or
callback = () => shescape.quoteAll([payload]);

const t0 = process.hrtime.bigint();
callback();
const ms = Number(process.hrtime.bigint() - t0) / 1e6;

// 4. Impact
console.log("Duration:", ms);
// Outputs "Duration:" followed by a number close to 20000

Patches

This bug has been patched in [v2.1.14] and [v3.0.1] which you can upgrade to now.

If you are already using v3 of Shescape, no further changes are required. If you are using v2 of Shescape it is recommended to upgrade as this version reaches end-of-life status on 2026-09-28, follow the [migration guide] to upgrade to v3.

No patches will be released for version of Shescape lower than v2.0.0.

Workarounds

Alternatively, users of Shescape can 1) put restrictions on the length of untrusted input or 2) strip all content before the last - from untrusted inputs.

For more information

Comment on Pull Request [#2651] for v2 and [#2649] for v3
Comment on commit [b4b34c3] for v2 and [43d70b5] for v3
Open an issue at https://github.com/ericcornelissen/shescape/issues (New issue > Question)

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`shescape`	≥ 2.1.11&&< 2.1.14	2.1.14`npm install shescape@2.1.14`
📦npm	`shescape`	≥ 3.0.0&&< 3.0.1	3.0.1`npm install shescape@3.0.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for shescape, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update shescape to 2.1.14 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73413 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Frequently Asked Questions

### Impact This impacts users of Shescape that have flag protection enabled, which is on by default, regardless of the API being used. An attacker can cause a runtime quadratic in the input size, causing denial of service for large inputs. ```javascript import { Shescape } from "shescape"; // 1. Prerequisites const options = { //flagProtection unspecified // Or flagProtection: true, }; // 2. Payload let payload = "\u0000-".repeat(32000); // 3. Usage const shescape = new Shescape(options); let callback; callback = () => shescape.escape(payload); // Or callback = () => shescap

O3 Security · Impact-Aware SCA

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