CVE-2021-35515 — commons-compress
HIGHCVE-2021-35515 is a high-severity (CVSS 7.5) CWE-834 vulnerability in org.apache.commons:commons-compress. 3 public exploit references exist, so weaponization risk is real. A fix is available for org.apache.commons:commons-compress — see the affected versions and patch details below.
Excessive Iteration in Compress
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-2021-35515 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 377,333 CVEs with a current EPSS score, this one falls in the 10–50% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
org.apache.commons:commons-compressReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.
Description
When reading a specially crafted 7Z archive, the construction of the list of codecs that decompress an entry can result in an infinite loop. This could be used to mount a denial of service attack against services that use Compress' sevenz package.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| ☕Maven | org.apache.commons:commons-compress | all versions | 1.21org.apache.commons:commons-compress:1.21 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
When reading a specially crafted 7Z archive, the construction of the lis…
When reading a specially crafted 7Z archive, the construction of the lis…
When reading a specially crafted 7Z archive, the construction of the lis…
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for org.apache.commons:commons-compress, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update org.apache.commons:commons-compress to 1.21 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-35515 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-2021-35515 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2021-35515. 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.
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Fuse 7.11 | apache-commons-compress | RHSA-2022:5532 |
| Red Hat Virtualization Engine 4.4 | apache-commons-compress-0:1.21-1.2.el8ev | RHSA-2022:5555 |
Frequently Asked Questions
Is CVE-2021-35515 in your dependencies?
O3 Security finds CVE-2021-35515 across Maven dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.