CVE-2021-29482
HIGHCVE-2021-29482 is a high-severity (CVSS 7.5) CWE-835 vulnerability in github.com/ulikunitz/xz. O3 Security confirms whether CVE-2021-29482 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
github.com/ulikunitz/xz fixes readUvarint Denial of Service (DoS)
Blast Radius
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 | 0.5.8 |
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. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
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 pinpoints whether CVE-2021-29482 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
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.
Frequently Asked Questions
Is CVE-2021-29482 in your dependencies?
O3 detects CVE-2021-29482 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.