Evidence used
- No CISA KEV confirmation is currently recorded.
- The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
- EPSS is 11.57% for the current model date.
BlackTreeCVE IntelligenceFull vulnerability report · 2021
CVE-2021-35515High confidence
Apache Commons Compress 1.6 to 1.20 denial of service vulnerability
Apache Software Foundation · Apache Commons Compress
7.5HighCVSS 3.1
Within 7 days
Patch availableHigh technical severity; prioritise exposed affected systems while verifying vendor guidance.
R
Open reassessment dashboard →Operational reassessment
Published severity in operational context
Published severityHigh→Operational priority:Critical, raised one band.upgradedsince 5 Oct 2026
Compensating controls
- Validate the affected product branch and deploy the verified fixed release.
- Restrict the affected network interface to trusted sources where business-safe.
- Monitor vendor guidance and exploitation sources for a material change.
Verification
- Confirm that the asset runs Apache Software Foundation Apache Commons Compress and falls inside the recorded affected range.
- Verify the installed build against the product-specific fixed version after deployment.
- Validate exposure, authentication requirements and compensating controls in the actual environment.
- Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Distribution package intelligence
5 package statesRelease-specific package status
Debian, ubuntu findings are scoped to the named distribution, release and source package. An absent finding does not mean a package is unaffected.
Repository candidate not checked
A published vendor fix does not prove that a matching update is enabled and installable on a particular asset. Confirm the local package candidate before scheduling remediation.
| Distribution release | Source package | Vendor state | Fixed version | Evidence |
|---|---|---|---|---|
| Debian trixietrixie · source | libcommons-compress-java | Vendor fix publishedDebian records a fixed source-package version for this release. | 1.21-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian bookwormbookworm · source | libcommons-compress-java | Vendor fix publishedDebian records a fixed source-package version for this release. | 1.21-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian forkyforky · source | libcommons-compress-java | Vendor fix publishedDebian records a fixed source-package version for this release. | 1.21-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Debian sidsid · source | libcommons-compress-java | Vendor fix publishedDebian records a fixed source-package version for this release. | 1.21-1 | Debian Security Tracker ↗Source updated 6 Oct 2026 |
| Ubuntu 24.04 LTSnoble · standard archive | libcommons-compress-java | Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing. | Not published in this feed | Canonical Ubuntu Security ↗Source updated 5 Oct 2026 |
Direct vendor intelligence
1 currentAuthoritative vendor CSAF and VEX advisories
Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.
CVE-2021-35515 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityapache-commons-compress: infinite loop when reading a specially crafted 7Z archive
The vendor explicitly identifies these products as affected by this CVE.
- apache-commons-compress.src as a component of Red Hat Decision Manager 7
- apache-commons-compress-javadoc as a component of Red Hat Enterprise Linux 7
- apache-commons-compress.src as a component of Red Hat Enterprise Linux 7
- apache-commons-compress-javadoc (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress-javadoc (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src as a component of Red Hat Process Automation 7
- rh-maven36-apache-commons-compress-javadoc as a component of Red Hat Software Collections
- rh-maven36-apache-commons-compress.src as a component of Red Hat Software Collections
- Summary
- A flaw was found in apache-commons-compress. 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 flaw allows the mounting of a denial of service attack against services that use Compress' SevenZ package. The highest threat from this vulnerability is to system availability.
- Remediation
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/2974891
High technical severity; prioritise exposed affected systems while verifying vendor guidance.
Patch available01
What, why and how
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.
What
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.
Why
The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
What
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.
Why
The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.
How
An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may disrupt the affected service.
02
Exploit reality and attack path
CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.
Observed exploitation No confirmed evidence
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.
Public PoC / exploit material None recorded
?
Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.No exploit-tagged reference or CISA SSVC proof-of-concept state is currently recorded. Research may still exist outside the structured feeds.
- Likely attack path
- a network path → Excessive Iteration → disrupt the affected service
- Attack surface
- Network
- Privileges required
- None: unauthenticated exploitation is possible
- User interaction
- None
- Attack complexity
- Low: no specialised conditions are recorded
- Security boundary
- Unchanged: impact remains within the vulnerable component's security authority
- Weakness
?
CWE means Common Weakness Enumeration: a standard category for the underlying weakness. - CWE-834 ↗
CWE-834: Excessive Iteration. The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.
- CVSS vector
?
CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity. CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HCommon Vulnerability Scoring System 3.1: the compact vector below is decoded into plain language.
AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.SUnchangedScope: The security impact remains within the vulnerable component's authority.CNoneConfidentiality impact: No direct loss is represented by this metric.INoneIntegrity impact: No direct loss is represented by this metric.AHighAvailability impact: A successful attack can cause a major loss.- Post-exploitation / living off the land
- No specific living-off-the-land technique is confirmed in the structured sources. Monitor normal administration tools for activity inconsistent with the affected service's baseline.
03
Patch and workaround
Operational remediation based on structured source evidence.
- Status
?
Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change. - Patch available
- Affected
- apache-commons-compress.src as a component of Red Hat Decision Manager 7
- apache-commons-compress-javadoc as a component of Red Hat Enterprise Linux 7
- apache-commons-compress.src as a component of Red Hat Enterprise Linux 7
- apache-commons-compress-javadoc (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress-javadoc (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress (eclipse:rhel8) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress (javapackages-tools:201801) as a component of Red Hat Enterprise Linux 8
- apache-commons-compress.src as a component of Red Hat Process Automation 7
- rh-maven36-apache-commons-compress-javadoc as a component of Red Hat Software Collections
- rh-maven36-apache-commons-compress.src as a component of Red Hat Software Collections
- Fixed
- apache-commons-compress-0:1.21-1.2.el8ev.noarch as a component of RHEL-8-RHEV-S-4.4 - Red Hat Virtualization Engine 4.4
- apache-commons-compress-0:1.21-1.2.el8ev.src as a component of RHEL-8-RHEV-S-4.4 - Red Hat Virtualization Engine 4.4
- apache-commons-compress-javadoc-0:1.21-1.2.el8ev.noarch as a component of RHEL-8-RHEV-S-4.4 - Red Hat Virtualization Engine 4.4
- Red Hat Fuse 7.11
- Action
- For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/2974891
- Workaround
- No verified workaround is recorded. If business-safe, reduce exposure to the affected interface and allow only trusted sources until authoritative guidance is available.
04
Evidence and provenance
Published 13 Jul 2021 · Last source change 4 Aug 2024, 00:40 UTC · CWE-834 · Excessive Iteration
CVE recordCVE.org · 5.1
CVSS sourceNIST NVD
EPSS source FIRST · tracked since 2026-08-14
?
The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.European sourceENISA EUVD · EUVD-2021-1620
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD modified after enrichment
Core structured fields are present and their contributing authorities are shown above.
Material change intelligence
View recent updates ↗What changed after publication
- Affected versionsThe structured affected or fixed version information changed.Red Hat Product Security ↗
- Before
- 1.6 < Apache Commons Compress* · Fixed: An authoritative update reference is available, but the fixed version is not recorded in the structured CVE fields. Check the linked vendor advisory for the applicable release.
- After
- 1.6 < Apache Commons Compress* · Fixed: For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/2974891
CVE published
Fixed release or patch reference recorded
Fixed release recorded from official guidance
Technical terms and abbreviations used in this report
- CVE
- Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
- CVSS
- Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
- EPSS
- Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
- CWE
- Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
- CNA
- CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
- CISA ADP
- Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
- NVD
- National Vulnerability Database: NIST's enrichment service for CVE records.
- CERT / CSIRT
- A computer security incident response team that publishes warnings or coordinates incident response.
- PoC
- Proof of concept: public material that demonstrates or helps reproduce exploitation.
- CSAF
- Common Security Advisory Framework: a machine-readable format for security advisories.
- LoTL
- Living off the land: abuse of legitimate tools or system functions during an attack.