CVE-2020-10378 is a medium-severity (CVSS 5.5) Out-of-bounds Read vulnerability in pillow. A fix is available for pillow — see the affected versions and patch details below.
Out-of-bounds read in Pillow
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-10378 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
pillowReal-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
In libImaging/PcxDecode.c in Pillow before 7.1.0, an out-of-bounds read can occur when reading PCX files where state->shuffle is instructed to read beyond state->buffer.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | pillow | all versions | 7.1.0pip install --upgrade 'pillow==7.1.0' |
Affected Products
ubuntu linuxcanonicalfedorafedoraprojectpillowpythonDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for pillow, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update pillow to 7.1.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-10378 is resolved across your whole dependency graph.
Workarounds
Stop feeding it untrusted input: reject or quarantine files and payloads from unverified sources until you can upgrade, restrict accepted formats to the ones you actually need, and run the parsing or decoding step in a least-privileged sandbox or short-lived worker so a crash or corrupted read cannot reach the rest of the process.
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.
Frequently Asked Questions
Is CVE-2020-10378 in your dependencies?
Find it across PyPI, including transitive dependencies.