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High, CVSS 8.7amended

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

CVE-2026-73413GHSA-gm3r-q2wp-hw87

What to do

Vendor fix available. Upgrade each affected package to the fixed version on its release line (shescape 3.0.1, 2.1.14), redeploy, then verify what is actually installed.

This page has no inventory attached, so it cannot say whether you are affected. A vendor fix is not proof that your deployment is fixed.

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Affected packages

  • npm shescape

    Affected
    >= 2.1.11, < 2.1.14>= 3.0.0, < 3.0.1
    Fixed in
    3.0.1, 2.1.14

Sources

Severity and exploitation
Exploitation
No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.
CVSS 4.0
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 · score source
EPSS
  • CVE-2026-73413: 0.59% estimated exploitation activity in the next 30 days; percentile 48.25 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.
Source description

As published by the source; long descriptions are shortened.

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. 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…

Dates and revisions
Published by the source
Last modified by the source
Source last checked
  1. Revision 3 · amended ·

    Amended from ghsa record GHSA-gm3r-q2wp-hw87

  2. Revision 2 · amended ·

    Reviewed OSV alias/range/CVSS4 correction; package source scopes and original publication preserved. No customer finding resolved.

  3. Revision 1 · created ·

    Published from osv record GHSA-gm3r-q2wp-hw87

Agent brief

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

# Patch Next advisory brief: CVE-2026-73413

Advisory: Shescape: Quadratic-time denial of service in the flag-protection
IDs: CVE-2026-73413, GHSA-gm3r-q2wp-hw87
Record: https://patchnext.com/advisories/cve-2026-73413 (revision 3, source checked 26 Oct 2026, 13:01 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 8.7)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: shescape 3.0.1, 2.1.14. A vendor fix does not mean a deployment is fixed.

## Affected components
- npm shescape: affected >= 2.1.11, < 2.1.14; >= 3.0.0, < 3.0.1; fixed in 3.0.1, 2.1.14

## Suggested inspection (read-only)
- `npm ls shescape --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 shescape.
- 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://osv.dev/vulnerability/GHSA-gm3r-q2wp-hw87 (OSV record GHSA-gm3r-q2wp-hw87 lists affected ranges: npm shescape >=2.1.11 =3.0.0 <3.0.1 (fixed))
- Verified: https://github.com/advisories/GHSA-gm3r-q2wp-hw87 (GitHub-reviewed advisory GHSA-gm3r-q2wp-hw87 lists affected ranges: npm shescape >=2.1.11 =3.0.0 <3.0.1)

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