CVE-2020-15106 is a medium-severity (CVSS 6.5) Improper Input Validation vulnerability in go.etcd.io/etcd/v3. A fix is available for go.etcd.io/etcd/v3 — see the affected versions and patch details below.
etcd's WAL `ReadAll` method vulnerable to an entry with large index causing panic
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2020-15106 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 378,156 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
go.etcd.io/etcd/v3🐹go.etcd.io/etcd/v3Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
Vulnerability type
Data Validation
Detail
In the ReadAll method in wal/wal.go, it is possible to have an entry index greater then the number of entries. This could cause issues when WAL entries are being read during consensus as an arbitrary etcd consensus participant could go down from a runtime panic when reading the entry.
References
Find out more on this vulnerability in the security audit report
For more information
If you have any questions or comments about this advisory:
- Contact the etcd security committee
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | go.etcd.io/etcd/v3 | all versions | 3.3.23go get go.etcd.io/etcd/v3@v3.3.23 |
| 🐹Go | go.etcd.io/etcd/v3 | ≥ 3.4.0&&< 3.4.10 | 3.4.10go get go.etcd.io/etcd/v3@v3.4.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for go.etcd.io/etcd/v3, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update go.etcd.io/etcd/v3 to 3.3.23 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-15106 is resolved across your whole dependency graph.
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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2020-15106 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2020-15106. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
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.
* In Red Hat OpenShift Container Platform (RHOCP), the affected components are behind OpenShift OAuth authentication. This restricts access to the vulnerable etcd to authenticated users only. * In Red Hat OpenStack Platform (RHOSP), the use of etcd is limited to the internal API network, which is not accessible to…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Enterprise Linux 7 Extras | etcd-0:3.2.32-1.el7_9 | RHSA-2021:1407 |
| Red Hat OpenShift Container Platform 4.8 | openshift4/ose-etcd:v4.8.0-202106152230.p0.git.aefa6bf.assembly.stream | RHSA-2021:2438 |
| Red Hat OpenStack Platform 16.1 | etcd-0:3.3.23-1.el8ost | RHSA-2021:0916 |
Frequently Asked Questions
Is CVE-2020-15106 in your dependencies?
O3 Security finds CVE-2020-15106 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.