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Not in CISA KEV
MEDIUM severity

CVE-2021-32091 — localstack

MEDIUM

CVE-2021-32091 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in localstack. 2 public exploit or proof-of-concept references are indexed, so weaponization risk is real. The records list no fixed version yet; check the vendor advisory below and apply the mitigations in the meantime.

Cross-site scripting in LocalStack

Also known asGHSA-37m5-42qp-4qprPYSEC-2021-102
Published
Updated
Affected
1 pkg
Patched
See advisory
Exploits
2 known
Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
0.8%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs58th percentile — riskier than 58% of all scored CVEsHighest risk
0.00%0.45%0.90%1.35%0.2%0.8%May 26Sep 26Nov 26

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

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐍localstack

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

A Cross-site scripting (XSS) vulnerability exists in StackLift LocalStack 0.12.6.

Affected Packages

1 total
EcosystemPackageVulnerable rangeFix
🐍PyPIlocalstackall versionsNo fix

Affected Products

1 product · 1 configurations
Application
localstacklocalstack
1 version
0.12.6
Exploits & PoCs
2

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

A Cross-site scripting (XSS) vulnerability exists in StackLift LocalStac…

portswigger.netNVDJun 2021

Report on blog.sonarsource.com

blog.sonarsource.comNVDJun 2021

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Remediation status

    The records we use list no patched version of localstack for CVE-2021-32091. Check the maintainer's advisory, and where your build allows, override or pin the dependency away from the vulnerable range.

  3. Mitigate without a patch

    Escape or sanitise the affected output on the server side rather than relying on client-side filtering, and add a Content-Security-Policy that blocks inline script execution so injected markup cannot run even if it reaches the page.

Frequently Asked Questions

A Cross-site scripting (XSS) vulnerability exists in StackLift LocalStack 0.12.6.
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CVE-2021-32091: localstack: Cross-site scripting