How severe is CVE-2016-10516?

CVE-2016-10516 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2016-10516?

CVE-2016-10516 affects the following packages: werkzeug (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2016-10516?

Update werkzeug to 0.11.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-10516 is resolved across your whole dependency graph.

How do I detect CVE-2016-10516 in my PyPI dependencies?

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

How do I mitigate CVE-2016-10516 if there is no patch (or I can't update yet)?

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.

Is CVE-2016-10516 actively exploited in the wild?

No public exploit code has been indexed for CVE-2016-10516 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-2016-10516?

CVE-2016-10516 has an EPSS (Exploit Prediction Scoring System) score of 2.0%, placing it in the 80th 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-2016-10516?

CVE-2016-10516 is classified as Cross-site Scripting (XSS) (CWE-79). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2016-10516 published, and has it been updated?

CVE-2016-10516 was published on October 23, 2017 and was last updated on October 20, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2016-10516 — werkzeug

MEDIUMFix: pallets/werkzeug#1001

CVE-2016-10516 is a medium-severity (CVSS 6.1) Cross-site Scripting (XSS) vulnerability in werkzeug. A fix is available for werkzeug — see the affected versions and patch details below.

Pallets Werkzeug cross-site scripting vulnerability

Also known asGHSA-h2fp-xgx6-xh6fPYSEC-2017-43

Published

Oct 23, 2017

Updated

Oct 20, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Exploitation data as of Oct 27, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

2.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs80th percentile — riskier than 80% of all scored CVEsHighest risk

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

🐍werkzeug

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

Cross-site scripting (XSS) vulnerability in the render_full function in debug/tbtools.py in the debugger in Pallets Werkzeug before 0.11.11 (as used in Pallets Flask and other products) allows remote attackers to inject arbitrary web script or HTML via a field that contains an exception message.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`werkzeug`	all versions	0.11.11`pip install --upgrade 'werkzeug==0.11.11'`

Affected Products

1 product · 1 configurations

Application

werkzeugpalletsprojects

< 0.11.11

range

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for werkzeug, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update werkzeug to 0.11.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2016-10516 is resolved across your whole dependency graph.
Workarounds
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.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

Product	Fixed in	Advisory
Red Hat Satellite 6.6 for RHEL 7	`ansiblerole-foreman_scap_client-0:0.0.3-1.el7sat`	RHSA-2019:3172

UbuntuMEDIUM

USN-3463-1Ubuntu

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2016-10516 in your dependencies?

Find it across PyPI, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

6.1/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

Required

Scope

Changed

Confidentiality

Low

Integrity

Low

Availability

None

Raw vector

CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE Classification

CWE-79Cross-site Scripting (XSS)

Weaponization

No Nuclei template, Metasploit module or public proof-of-concept found.

OpenSSF Scorecard

Package health score

werkzeug

6.0/10

Code-Review0/10

Maintained10/10

Branch-Protection3/10

Assessed Oct 19, 2026

Timeline

Disclosed

Oct 23, 2017

Last updated

Oct 20, 2026

Identifiers

CVE-2016-10516

GHSA-h2fp-xgx6-xh6f

PYSEC-2017-43

References

Advisorygithub.com Advisorynvd.nist.gov · CVE 2016 10516 Advisorygithub.com · GHSA h2fp xgx6 xh6f Reportblog.neargle.com · flask src review get a xss from debuger Weblists.debian.org · msg00037 Webgithub.com · 1034edc7f901dd645ec6e462754111b39002bd65 Webgithub.com · PYSEC 2017 43.yaml Webblog.neargle.com · flask src review get a xss from debuger Packagegithub.com · werkzeug

Related vulnerabilities

Also affects werkzeug

This CVE is medium severity; 5 of 5 other CVEs affecting werkzeug are rated as high or higher (top: high).

CVE-2026-27199CVE-2025-66221CVE-2019-14322CVE-2020-28724CVE-2019-14806

Same weakness: CWE-79

This CVE is medium severity; 3 of 3 other CVEs with CWE-79 are rated as high or higher (top: critical).

CVE-2026-44267CVE-2026-96632CVE-2026-9086Browse all CWE-79

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedOct 20, 2026