How severe is CVE-2021-35515?

CVE-2021-35515 has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-35515?

CVE-2021-35515 affects the following packages: org.apache.commons:commons-compress (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-35515?

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.

How do I detect CVE-2021-35515 in my Maven dependencies?

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.

How do I mitigate CVE-2021-35515 if there is no patch (or I can't update yet)?

Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Is CVE-2021-35515 actively exploited in the wild?

Yes. There are 3 known exploit references for CVE-2021-35515, including 3 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-35515?

CVE-2021-35515 has an EPSS (Exploit Prediction Scoring System) score of 11.6%, placing it in the 96th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score warrants monitoring and prompt remediation.

What type of vulnerability is CVE-2021-35515?

CVE-2021-35515 is classified as CWE-834 (CWE-834), CWE-835 (CWE-835). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-35515 published, and has it been updated?

CVE-2021-35515 was published on July 13, 2021 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

HIGH severity

CVE-2021-35515 — commons-compress

HIGH

CVE-2021-35515 is a high-severity (CVSS 7.5) CWE-834 vulnerability in org.apache.commons:commons-compress. 3 public exploit or proof-of-concept references are indexed, 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

Also known asGHSA-7hfm-57qf-j43q

Published

Jul 13, 2021

Updated

Oct 24, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

3 known

Exploitation data as of Oct 31, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

11.6%probability of exploitation in next 30 days

Moderate Risk0.00%

Lower risk than most CVEs96th percentile — riskier than 96% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected

☕org.apache.commons:commons-compress

Real-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

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`org.apache.commons:commons-compress`	all versions	1.21`org.apache.commons:commons-compress:1.21`

Affected Products

26 products · 47 configurations

Application

commons compressapache

≥ 1.6 && ≤ 1.20

range

Application

active iq unified managernetapp

all

Application

oncommand insightnetapp

all

Application

banking digital experienceoracle

≥ 18.1 && ≤ 18.3

3 versions

19.120.121.1

Application

banking enterprise default managementoracle

1 version

2.7.0

Application

banking party managementoracle

1 version

2.7.0

Exploits & PoCs

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…

lists.apache.orgNVDDec 2021

Report on lists.apache.org

lists.apache.orgNVDDec 2021

Report on lists.apache.org

lists.apache.orgNVDDec 2021

Detection & mitigation playbook

Open-source dependency

Detect
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
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

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.

Red HatModerate

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

O3 Security · Impact-Aware SCA

Is CVE-2021-35515 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVE-2021-35515 — commons-compress

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Fixing This On Your OS

Frequently Asked Questions

Is CVE-2021-35515 in your dependencies?