BlackTreeIndependent security intelligence

Full vulnerability report · 2026

CVE-2026-85396High confidence

rubyzip before 3.4.0 Path Traversal in Zip::Entry#extract via Sibling-Directory Prefix

rubyzip · rubyzip

8.7HighCVSS 4.0

Recommended action

Within 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

Distribution package intelligence

Ubuntu vendor package status

Canonical’s release and source-package findings are shown separately from local repository availability.

1 package state

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.

Ubuntu release	Source package	Vendor state	Fixed version	Evidence
Ubuntu 24.04 LTSnoble · standard archive	`ruby-zip`	Under evaluationCanonical reports that the package might be affected and still needs evaluation or fixing.	`Not published in this feed`	Canonical record ↗Source updated 8 Sept 2026

Direct vendor intelligence

Authoritative 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.

1 current

CVE-2026-85396 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityrubyzip: rubyzip: Arbitrary file write via path traversal

4 known not affected

The vendor explicitly states that these products are not affected by this CVE.

3scale-amp2/backend-rhel8 as a component of Red Hat 3scale API Management Platform 2
3scale-amp2/system-rhel8 as a component of Red Hat 3scale API Management Platform 2
3scale-amp2/system-rhel9 as a component of Red Hat 3scale API Management Platform 2
3scale-amp2/toolbox-rhel9 as a component of Red Hat 3scale API Management Platform 2

Summary: A flaw was found in rubyzip. This path traversal vulnerability in the Zip::Entry#extract function allows a remote attacker to craft malicious archive entries. By failing to properly validate extraction paths, the vulnerability enables an attacker to write files outside the intended extraction directory, potentially leading to arbitrary file write.
Remediation: No remediation text is recorded.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current

ENISA EUVD identifier

EUVD-2026-70673

No EUVD known-exploited evidence

rubyzip versions before 3.4.0 contain a path traversal vulnerability in Zip::Entry#extract that fails to properly validate extraction paths using prefix comparison without trailing separators. Attackers can craft archive entries with names like ../upload_backup/owned.sh to write files outside the intended extraction directory into sibling paths sharing the destination prefix.

EUVD state: Present in the current official mapping
Known exploitation: Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score: 8.7 · CVSS 4.0
Advisory evidence: No linked advisory details stored yet

Recommended actionWithin 7 days

High technical severity; prioritise exposed affected systems while verifying vendor guidance.

Patch available

What, why and how

What

Why

Attacker-controlled path data is not constrained to the intended directory before the application accesses a file.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may cause the confidentiality, integrity or availability impact described by the vendor.

What

Why

Attacker-controlled path data is not constrained to the intended directory before the application accesses a file.

How

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

No confirmed evidence

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

Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.

None recorded

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 → Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') → cause the confidentiality, integrity or availability impact described by the vendor
Attack surface: Network
Privileges required: None: unauthenticated exploitation is possible
User interaction: None
Attack complexity: Low: no specialised conditions are recorded
Security boundary: Not a CVSS 4.0 base metric
Weakness ? CWE means Common Weakness Enumeration: a standard category for the underlying weakness.: CWE-22 ↗
CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal'). The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CVSS vector ? CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
Common Vulnerability Scoring System 4.0: 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.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCNoneVulnerable-system confidentiality: No direct loss is represented by this metric.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VANoneVulnerable-system availability: No direct loss is represented by this metric.SCNoneSubsequent-system confidentiality: No direct loss is represented by this metric.SINoneSubsequent-system integrity: No direct loss is represented by this metric.SANoneSubsequent-system availability: No direct loss is represented by this metric.
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.

NetworkUnauthenticatedCWE-22

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-70673Official EUVD mapping

Official EUVD record

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: < 3.4.0
Fixed: 3.4.0
Action: Review the linked authoritative reference and apply the recorded fixed release appropriate to the affected product branch.
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.

Evidence and provenance

Published 3 Sept 2026 · Last source change 3 Sept 2026, 19:00 UTC · CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVE recordCVE.org · 5.2

CVSS sourceCNA

EPSS source

The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.

FIRST · tracked since 2026-09-04

European sourceENISA EUVD · EUVD-2026-70673

Product sourceCNA

Remediation sourceCVE/CNA references

CWE sourceCNA

NVD statusNVD received

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates →

4 Sept 2026, 13:40 UTC
ENISA EUVD mappingEUVD-2026-70673 was added to the official ENISA EUVD mapping for this CVE.
Before
not recorded
After
{"euvdId":"EUVD-2026-70673"}
ENISA EUVD ↗
3 Sept 2026, 19:00 UTC
Catalogue recordCVE added to the BlackTree catalogue.
CNA ↗

2026-09-03CVE published

2026-09-03Fixed release or patch reference recorded

ENISA EUVD · EUVD-2026-70673↗Vendor CSAF · Red Hat Product Security↗CVE authority or vendor reference↗Official CVE record (CNA and ADP data)↗NVD record↗

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.