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HIGH severity

CVE-2021-39371 — pywps

HIGHFix: geopython/pywps#616

CVE-2021-39371 is a high-severity (CVSS 7.5) XML External Entity (XXE) vulnerability in pywps. A fix is available for pywps — see the affected versions and patch details below.

XML External Entity Injection in PyWPS

Also known asGHSA-p9wf-3xpg-c9g5PYSEC-2021-121
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Oct 9, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗
1.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs74th percentile — riskier than 74% of all scored CVEsHighest risk
0.03%0.69%1.36%2.02%0.5%1.5%Apr 26Aug 26Oct 26

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

How urgent is this, really

CVE-2021-39371 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 385,386 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected
🐍pywps

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

An XML external entity (XXE) injection in PyWPS before 4.4.5 allows an attacker to view files on the application server filesystem by assigning a path to the entity. OWSLib 0.24.1 may also be affected.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPIpywpsall versions4.5.0pip install --upgrade 'pywps==4.5.0'

Affected Products

3 products · 3 configurations
OS
debian linuxdebian
1 version
9.0
Application
owslibosgeo
1 version
0.24.1
Application
pywpsosgeo
< 4.4.5
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

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

  2. Fix

    Update pywps to 4.5.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-39371 is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

An XML external entity (XXE) injection in PyWPS before 4.4.5 allows an attacker to view files on the application server filesystem by assigning a path to the entity. OWSLib 0.24.1 may also be affected.
O3 Security · Impact-Aware SCA

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CVE-2021-39371: pywps XXE — Fixed in 4.5.0