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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Craft archive with traversal paths
  2. Delivery
    Deliver malicious archive to victim
  3. Exploit
    Victim extracts archive via Libarchive
  4. Execution
    Files written outside target directory
  5. Impact
    Tamper with files on disk

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A01:2025 - Broken Access Control
ASVS 5.0
V5 - File Handling Relative path traversal prevention
Exploitation Conditions

Exploitation requires a victim to open or extract an attacker-supplied malicious archive using the Libarchive component bundled in Windows (UI:R) - it is not triggerable without that user action. The vulnerability is network-deliverable (the archive can be sent remotely) and requires no authentication or prior privileges on the target (PR:N), but the mandatory user interaction and the fact that it is not automatable (SSVC: Automatable=no) are the key limiting factors, confining realistic attacks to social-engineering or supply-of-file scenarios rather than unattended remote compromise. Impact is limited to integrity (file tampering/write outside intended path); there is no confidentiality or availability impact.

Impact

This is a medium-severity (CVSS 6.5) relative path traversal (CWE-23) in the Libarchive component shipped with Windows. The CVSS 3.1 vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N indicates network-reachable, low-complexity, unauthenticated exploitation but critically requires user interaction (UI:R) and yields only integrity impact (I:H) with no confidentiality or availability loss - consistent with an attacker overwriting/placing files outside the intended extraction directory when a victim processes a malicious archive. Multiple exploitation signals align toward LOWER real-world urgency: it is NOT listed in CISA KEV, no public POC is referenced, and CISA's SSVC framework rates Exploitation as 'none', Automatable as 'no', and Technical Impact as 'partial'. The SSVC 'not automatable' and UI:R requirement both argue against mass/wormable exploitation, pointing instead to targeted, social-engineering-dependent abuse. There is no conflict between the signals here - raw CVSS, SSVC, and the absence of KEV/POC all converge on a 'real but not emergency' patch-in-normal-cycle priority, elevated mainly by the enormous Windows install base rather than by active exploitation.

Exploit ScenarioDerived

An attacker crafts a malicious archive (e.g., ZIP/TAR) containing entries with relative path traversal sequences and delivers it to a victim via email, download, or a shared location. When the victim extracts or processes the archive using the vulnerable Windows Libarchive component, files are written outside the intended directory, enabling tampering such as overwriting configuration or dropping files into sensitive paths. No public exploit code is identified at time of analysis, and successful attack depends on the victim actively processing the attacker-supplied archive (UI:R).

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.8% exploitation probability (EPSS)

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AnalysisAIv1 – Oct 14, 2026

Relative path traversal (CWE-23) in the Libarchive component shipped with Windows lets an unauthenticated remote attacker tamper with files on a target system if they can convince a user to open or extract a crafted archive - a condition reflected in the CVSS vector's UI:R requirement. Affected are supported Windows client and server builds below their respective patched levels, including Windows 10 (1809, 21H2, 22H2), Windows 11 (23H2, 24H2, 25H2, 26H1, 26H2), Windows Server 2019, Windows Server 2022, and Windows Server 2025 (including Server Core installations); impact is integrity-only (no confidentiality or availability effect), and the assessment notes no confirmed active exploitation (not in CISA KEV), no publicly available exploit code identified at time of analysis, and CISA SSVC rating Exploitation=none, Automatable=no, Technical Impact=partial. Vendor patch is available, making this a medium-severity (CVSS 6.5) issue that should be remediated through standard Windows update cycles.

RemediationAI

Apply the vendor security update - patch status is "available from vendor," and per the EUVD ranges the fixed builds are Windows 10 1809 and Server 2019 at 10.0.17763.9376, Windows 10 21H2/22H2 at 10.0.19044.7807, Windows 11 23H2 at 10.0.22631.7652, Windows 11 24H2 and Server 2025 at 10.0.26100.33650/10.0.26100.9711 respectively, Windows 11 25H2 at 10.0.26200.9711, Windows 11 26H1 at 10.0.28000.3231, Windows 11 26H2 at 10.0.26300.9711, and Windows Server 2022 at 10.0.20348.5761; consult and follow the Microsoft MSRC advisory at https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-69968 for the authoritative per-build guidance and supersedence. If updates cannot be deployed immediately, compensating controls should target the user-interaction prerequisite rather than the network path, since the archive is only dangerous once extracted: restrict or block extraction of untrusted archives on high-value endpoints using application control or policy that limits which tools can unpack files (trade-off: breaks legitimate archive-heavy workflows and requires allowlisting maintenance), and require that archives from external senders be opened inside a disposable sandboxed VM or low-privilege container with no write access to sensitive paths (trade-off: operational overhead and slower handling of routine files). Email and web gateways can be tuned to quarantine archive attachments and archive downloads, which reduces delivery but cannot sanitize malicious entry names if a user obtains the file by other means, and enforcing least-privilege user accounts limits the blast radius of any out-of-directory write. Because exploitation is not automatable per SSVC, user awareness messaging about opening unexpected archives remains a useful secondary control; no public exploit code has been identified at time of analysis, so prioritization should follow normal patch-cycle timelines for a CVSS 6.5 integrity-only issue.

Affected VersionsENISA

Windows 10 Version 1809 10.0.17763.0 <10.0.17763.9376
Windows Server 2025 10.0.26100.0 <10.0.26100.33650
Windows Server 2025 (Server Core installation) 10.0.26100.0 <10.0.26100.33650
Windows 10 Version 22H2 10.0.19045.0 <10.0.19044.7807
Windows Server 2019 (Server Core installation) 10.0.17763.0 <10.0.17763.9376
Windows 11 Version 26H2 10.0.26300.0 <10.0.26300.9711
Windows Server 2019 10.0.17763.0 <10.0.17763.9376
Windows Server 2022 10.0.20348.0 <10.0.20348.5761
Windows 10 Version 21H2 10.0.19044.0 <10.0.19044.7807
Windows 11 version 26H1 10.0.28000.0 <10.0.28000.3231
Windows 11 Version 25H2 10.0.26200.0 <10.0.26200.9711
Windows 11 Version 23H2 10.0.22631.0 <10.0.22631.7652
Windows 11 Version 24H2 10.0.26100.0 <10.0.26100.9711

Affected Packages

euvd windows_10_version_1809 fix: 10.0.17763.9376
euvd windows_10_version_21h2 fix: 10.0.19044.7807
euvd windows_10_version_22h2 fix: 10.0.19044.7807
euvd windows_11_version_23h2 fix: 10.0.22631.7652
euvd windows_11_version_24h2 fix: 10.0.26100.9711
euvd windows_11_version_25h2 fix: 10.0.26200.9711
euvd windows_11_version_26h1 fix: 10.0.28000.3231
euvd windows_11_version_26h2 fix: 10.0.26300.9711
euvd windows_server_2019 fix: 10.0.17763.9376
euvd windows_server_2019_server_core_installation fix: 10.0.17763.9376
euvd windows_server_2022 fix: 10.0.20348.5761
euvd windows_server_2025 fix: 10.0.26100.33650
euvd windows_server_2025_server_core_installation fix: 10.0.26100.33650

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 13 packages in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

Libarchive is an open-source archive and compression library (the same codebase behind bsdtar) that Microsoft bundles into Windows to handle formats such as ZIP, 7z, tar, cab, and others. The flaw is classified as CWE-23 (Relative Path Traversal), often described in archive tooling as "zip slip": entry names inside an attacker-supplied archive that contain relative traversal sequences (for example "..\..\" or "../") are not sufficiently sanitized before the extraction path is constructed, so files are written outside the intended destination directory. Because the library processes attacker-controlled filename metadata rather than file contents, no memory-corruption or code-execution primitive is involved - the consequence is unauthorized file creation or overwrite (tampering). The assessed vector CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N indicates the malicious archive is network-deliverable and exploitable without authentication or privileges, but that success depends on a victim opening or extracting the archive, and that only integrity is impacted. EUVD tracks the issue as EUVD-2026-99122 and reports it via secure@microsoft.com; the SSVC decision framework classifies it as not automatable, which reinforces that exploitation cannot proceed unattended and instead requires a social-engineering or user-supplied-file step.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

Vendor (microsoft) PRIMARY 6.5 MEDIUM
AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
vuln.today AI 6.5 MEDIUM

Archive is network-deliverable (AV:N) and needs no auth (PR:N) but the victim must process it (UI:R); path traversal enables file tampering only, so I:H with C:N/A:N.

3.1 AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N
4.0 AV:N/AC:L/AT:N/PR:N/UI:A/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (microsoft).

CVSS VectorVendor: microsoft

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

Lifecycle Timeline

2
Patch available
Oct 13, 2026 - 20:20 EUVD
CVE Published
Oct 13, 2026 - 19:19 cve.org
MEDIUM 6.5

DescriptionCVE.org

Relative path traversal in Windows Libarchive allows an unauthorized attacker to perform tampering over a network.

Threat Intelligence Overview

EPSS Score
0.8%
Top 45% exploitable
Prevalence
Ubiquitous
Libarchive component ships in all supported Windows and Windows Server editions
Vendor Status
Publicly Disclosed:No
Exploited:No
Latest Software Release:Exploitation Less Likely
Data Quality
5 sources
Confidence: Medium

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.8%
Patch available Yes
Active threat No
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

33
Low Medium High Critical
KEV: 0
EPSS: +1
CVSS: +32
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

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