CVE-2021-29482 is a high-severity (CVSS 7.5) CWE-835 vulnerability in github.com/ulikunitz/xz. A fix is available for github.com/ulikunitz/xz — see the affected versions and patch details below.
github.com/ulikunitz/xz fixes readUvarint Denial of Service (DoS)
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-2021-29482 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 377,238 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
github.com/ulikunitz/xzReal-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
xz is a compression and decompression library focusing on the xz format completely written in Go. The function readUvarint used to read the xz container format may not terminate a loop provide malicous input. The problem has been fixed in release v0.5.8. As a workaround users can limit the size of the compressed file input to a reasonable size for their use case. The standard library had recently the same issue and got the CVE-2020-16845 allocated.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/ulikunitz/xz | all versions | 0.5.8go get github.com/ulikunitz/xz@v0.5.8 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/ulikunitz/xz, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/ulikunitz/xz to 0.5.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-29482 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-2021-29482 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-29482. 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 OpenShift Container Platform (OCP), OpenShift ServiceMesh (OSSM) and Red Hat Advanced Cluster Management for Kubernetes (RHACM) the affected components are behind OpenShift OAuth authentication, therefore the impact is low. In OCP before 4.7 the buildah, skopeo and podman packages include vulnerable version of…
| Product | Fixed in | Advisory |
|---|---|---|
| OADP-1.0-RHEL-8 | oadp/oadp-velero-plugin-rhel8:1.0.1-5 | RHSA-2022:0687 |
| OpenShift Service Mesh 2.0 | servicemesh-0:2.0.9-3.el8 | RHSA-2022:1276 |
| Red Hat OpenStack Platform 16.2 | rhosp-rhel8-tech-preview/osp-director-operator:1.2.3-2 | RHSA-2022:2183 |
| RHEL-8-CNV-4.8 | container-native-virtualization/vm-import-operator-rhel8:v4.8.0-18 | RHSA-2021:2920 |
Frequently Asked Questions
Is CVE-2021-29482 in your dependencies?
O3 Security finds CVE-2021-29482 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.