Shescape: Shell injection via unescaped parentheses on Windows with CMD

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

No collected risk observation for these identifiers. This does not establish absence of exploitation or a zero probability.

Shescape is a simple shell escape library for JavaScript. Prior to 2.1.14 and 3.0.1, getEscapeFunction in src/internal/win/cmd.js does not escape `(` and `)` when applications use the escape or escapeAll APIs on Windows with shell set to cmd.exe, or with shell set to true when CMD is the default. An attacker-controlled argument can break out of a parenthesized CMD construct and inject shell syntax depending on the original command, resulting in arbitrary command execution. This issue is fixed in versions 2.1.14 and 3.0.1.

Source published

12 Aug 2026 19:42:55 UTC

Source modified

14 Aug 2026 22:11:29 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: cve-program · CVE Program Terms of Use. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · 9.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Shescape is a simple shell escape library for JavaScript. Prior to 2.1.14 and 3.0.1, getEscapeFunction in src/internal/win/cmd.js does not escape `(` and `)` when applications use the escape or escapeAll APIs on Windows with shell set to cmd.exe, or with shell set to true when CMD is the default. An attacker-controlled argument can break out of a parenthesized CMD construct and inject shell syntax depending on the original command, resulting in arbitrary command execution. This issue is fixed in versions 2.1.14 and 3.0.1.

Source published

12 Aug 2026 20:17:56 UTC

Source modified

24 Oct 2026 15:10:00 UTC

Observed here

25 Oct 2026 15:19:09 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 4.0 · [email protected] · Secondary · 9.2 CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

### Impact This impacts users of Shescape on Windows that explicitly configure `shell` to CMD, or `true` with the default shell being CMD, using the `escape` and `escapeAll` APIs. An attacker may be able to achieve shell injection depending on the original command. ```javascript import * as cp from "node:child_process"; import { Shescape } from "shescape"; // 1. Prerequisites const options = { shell: "cmd.exe", // Or shell: true, // Only if the default shell is CMD }; // 2. Payload const payload = "x) else if a==a (echo y"; // 3. Usage const shescape = new Shescape(options); let escapedPayload; escapedPayload = shescape.escape(payload); // Or escapedPayload = shescape.escapeAll([payload]); // And (example) const result = cp.execSync(`if defined FALSY (echo ${escapedPayload})`, options); // 4. Impact console.log(result.toString()); // Outputs "y" instead of "" ``` ### 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 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 remove all instances of `(` and `)` 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)

Source published

24 Jul 2026 22:34:23 UTC

Source modified

12 Aug 2026 19:59:13 UTC

Observed here

24 Oct 2026 13:17:17 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V4 · CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Publisher rating · CRITICAL