CVE Intelligence
Medium Injection

CVE-2026-107353 — traverse: set() can write to built-in prototypes via an untrusted path

traverse (npm) versions 0.3.6 through 0.3.9, 0.4.0 through 0.4.6, 0.5.0 through 0.5.2, and 0.6.0 through 0.6.11 allow prototype pollution through set(). When the path passed to set() crosses a primitive value, the next path segment is resolved on that primitive's built-in prototype, so an application that passes an untrusted path to set() lets an attacker add or overwrite properties of String.prototype, Number.prototype, or Boolean.prototype using plain JSON data, for example traverse({ name: 'bob' }).set(['name', '__proto__', 'polluted'], 'yes'). Object.prototype was reachable only with a non-data path segment, such as an object whose toString returns a different value on each call, or through a Proxy that accepts an assignment without storing it. This is fixed in 0.3.10, 0.4.7, 0.5.3, and 0.6.12.

Published Oct 7, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: harborist

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
  • EPSS 0.3% (30-day exploitation probability)+3
  • Technical severity (medium)+3
  • 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
0.28%
ahead of 19% of scored CVEs · Oct 15, 2026
Affects
Ljharb
Traverse
CVSS base
6.5
Medium · 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
Partial
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 (Ljharb Traverse).
  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. Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

VendorProductVersionsStatusSource
Ljharb Traverse ≥ 0.3.6 and < 0.3.10≥ 0.4.0 and < 0.4.7≥ 0.5.0 and < 0.5.3≥ 0.6.0 and < 0.6.12 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
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
Low

Every base score collected

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

ScoreVersionSeverityExpl.ImpactScored by
6.9 CVSS 4.0 Medium — — 7ffcee3d-2c14-4c3e-b844-86c6a321a158 via NIST National Vulnerability Database
6.9 CVSS 4.0 Medium — — harborist via CVE Program (cve.org) e CISA ADP
6.5 CVSS 3.1 Medium 3.9 2.5 7ffcee3d-2c14-4c3e-b844-86c6a321a158 via NIST National Vulnerability Database
6.5 CVSS 3.1 Medium — — harborist via CVE Program (cve.org) e CISA ADP
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:L (score shown at the top: 7ffcee3d-2c14-4c3e-b844-86c6a321a158)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-1321 · Prototype Pollution

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 0.28%

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).
  • Look for parameters with command/query metacharacters and unexpected child processes of the service.
web/proxy/WAF logsnetwork IDS/IPSapplication logsendpoint telemetry (EDR)

Timeline

What happened to this CVE, newest first.

  • 2026
  • Affected products added · ljharb/traverse
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • SSVC assessment updated
    Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
  • Record published
    Oct 13, 2026
  • CVSS changed · 6.5
    Oct 13, 2026 · NIST National Vulnerability Database
  • Source status changed · → Awaiting Analysis
    Oct 13, 2026 · NIST National Vulnerability Database
  • Record created in this database
    Oct 13, 2026 · NIST National Vulnerability Database
  • CVE published
    Oct 7, 2026 · harborist

Source activity

Repeated readings are counted rather than listed.

  • 1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

Elsewhere on this site

Ljharb
every CVE for this vendor
Injection
same class
CWE-1321
other pages naming this weakness

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 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-2026-107353 is "traverse: set() can write to built-in prototypes via an untrusted path", rated Medium. It affects Traverse (Ljharb); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 6.5 describes technical severity. EPSS 0.28% estimates the probability of exploitation in 30 days; neither replaces your asset context. 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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