CVE Intelligence
High File handling

CVE-2026-86541 — knowns before 0.30.0 Path Traversal via code.replace MCP action

knowns versions before 0.30.0 contain a path traversal vulnerability in the handleCodeReplace() function that allows attackers to overwrite arbitrary files outside the project root. Attackers can supply absolute paths or relative paths containing directory traversal sequences to write malicious content to sensitive files like shell startup scripts or SSH configuration files.

Published Sep 7, 2026 · Updated Oct 15, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: VulnCheck

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.
How the score was calculated
  • Technical severity (high)+6
  • Automatable exploitation (SSVC)+3

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation
Not confirmed
Not in CISA KEV — an absence of record, not proof it is unexploited.
EPSS FIRST
—
No EPSS score.
Affects
Knowns-dev
Knowns
CVSS base
8.3
High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation
None
none · proof-of-concept · active
Automatable
Yes
can an attacker script the kill-chain steps
Technical impact
Total
partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

  1. Identify exposed assets running the affected vendor/product/version combinations (Knowns-dev Knowns).
  2. The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
  3. No fix documented in the sources: reduce exposure and monitor the vendor advisory.
  4. Exploitation requires user interaction: tighten email/web filtering and warn affected users.
  5. Search available logs for exploit probes matching the vulnerability class (file handling), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Knowns-dev Knowns < 0.30.0 Vulnerable CVE Program (cve.org) e CISA ADP

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
Low
Integrity
High
Availability
High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

ScoreVersionSeverityExpl.ImpactScored by
7.2 CVSS 4.0 High — — disclosure@vulncheck.com via NIST National Vulnerability Database
7.2 CVSS 4.0 High — — VulnCheck via CVE Program (cve.org) e CISA ADP
8.3 CVSS 3.1 High 2.8 5.5 disclosure@vulncheck.com via NIST National Vulnerability Database
8.3 CVSS 3.1 High — — VulnCheck via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:H/A:H (score shown at the top: disclosure@vulncheck.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-22 · Path Traversal

Other CVEs with this weakness →

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

  • Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
  • Monitor file creation in web directories and paths with traversal sequences (../).
web/proxy/WAF logsnetwork IDS/IPSfile integrity (FIM)endpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · knowns-dev/knowns
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 15, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 15, 2026
  • CVSS changed · 8.3
    Oct 15, 2026 · NIST National Vulnerability Database
  • Source status changed · → Deferred
    Oct 15, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 15, 2026 · NIST National Vulnerability Database
  • CVE published
    Sep 7, 2026 · VulnCheck

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 15, 2026 – Oct 15, 2026

References

5 on the record

Elsewhere on this site

Knowns-dev
every CVE for this vendor
File handling
same class
CWE-22
other pages naming this weakness

Related CVEs (same products)

  • CVE-2026-88899 knowns before 0.31.0 External Control of Agent Working Directory via x-opencode-directory Header Sep 10, 2026
  • CVE-2026-88937 knowns through 0.33.0 Path Traversal via Template Engine Sep 10, 2026
  • CVE-2026-88938 knowns through 0.33.0 Path Traversal via code.find MCP tool Sep 10, 2026
  • CVE-2026-88939 knowns through 0.33.0 Authorization Bypass via project.set Bootstrap Exemption Sep 10, 2026
  • CVE-2026-88940 knowns through 0.33.0 Arbitrary Directory Enumeration via workspace browse endpoint Sep 10, 2026
  • CVE-2026-86775 knowns before 0.30.0 Path Traversal via Document API Sep 9, 2026

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

  • No FIRST EPSS score.
  • No fixed version, patch or mitigation documented.
  • No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
  • No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
  • No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-86541 is "knowns before 0.30.0 Path Traversal via code.replace MCP action", rated High. It affects Knowns (Knowns-dev); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.3 describes technical severity. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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