NVD / CVE Program· CNA GitHub_M

CVE-2021-39134: UNIX Symbolic Link (Symlink) Following in @npmcli/arborist

Noroxi assessment

Priority: Monitor (action score 31/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.58% (FIRST EPSS).
Someone with local access to the system can trigger it. No account or password is required. A user must open a link or visit a page. No special conditions are required; it is repeatable.
Fixed version: nodejs (Alpine:v3.11) 12.22.6-r0; nodejs (Alpine:v3.13) 14.17.6-r0; npm (Debian:12) 7.24.0+ds-2.
Mentioned 1 time in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to nodejs (Alpine:v3.11) 12.22.6-r0; nodejs (Alpine:v3.13) 14.17.6-r0; npm (Debian:12) 7.24.0+ds-2 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

`@npmcli/arborist`, the library that calculates dependency trees and manages the `node_modules` folder hierarchy for the npm command line interface, aims to guarantee that package dependency contracts will be met, and the extraction of package contents will always be performed into the expected folder. This is, in part, accomplished by resolving dependency specifiers defined in `package.json` manifests for dependencies with a specific name, and nesting folders to resolve conflicting dependencies. When multiple dependencies differ only in the case of their name, Arborist's internal data structure saw them as separate items that could coexist within the same level in the `node_modules` hierarchy. However, on case-insensitive file systems (such as macOS and Windows), this is not the case. Combined with a symlink dependency such as `file:/some/path`, this allowed an attacker to create a situation in which arbitrary contents could be written to any location on the filesystem. For example, a package `pwn-a` could define a dependency in their `package.json` file such as `"foo": "file:/some/path"`. Another package, `pwn-b` could define a dependency such as `FOO: "file:foo.tgz"`. On case-insensitive file systems, if `pwn-a` was installed, and then `pwn-b` was installed afterwards, the contents of `foo.tgz` would be written to `/some/path`, and any existing contents of `/some/path` would be removed. Anyone using npm v7.20.6 or earlier on a case-insensitive filesystem is potentially affected. This is patched in @npmcli/arborist 2.8.2 which is included in npm v7.20.7 and above.

HighCVSS 7.8 · v3.1—No exploit Fix available

Published: Aug 31, 2021
Updated: Jun 17, 2026
EPSS: 0.5% · 48th percentile
CWE: CWE-61

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 31 / 40 · 7.8 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.5%

CNA vs NVD score

NVD: 7.8
CNA · GitHub_M: 8.2; 0.4 point gap

CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
npmjs	arborist	cpe:2.3:a:npmjs:arborist
npmjs	npm	cpe:2.3:a:npmjs:npm
oracle	graalvm	cpe:2.3:a:oracle:graalvm
siemens	sinec infrastructure network services	cpe:2.3:a:siemens:sinec_infrastructure_network_services

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

npmjs arboristbefore 2.8.2
oracle graalvm20.3.3
oracle graalvm21.2.0
siemens sinec infrastructure network servicesbefore 1.0.1.1

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

npm arborist
- < 2.8.2affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Alpine:v3.11	nodejs	before 12.22.6-r0	12.22.6-r0
Alpine:v3.13	nodejs	before 14.17.6-r0	14.17.6-r0
Debian:12	npm	before 7.24.0+ds-2	7.24.0+ds-2
npm	@npmcli/arborist	before 2.8.2	2.8.2
openSUSE:Leap 15.2	nodejs12	before 12.22.7-lp152.3.21.1	12.22.7-lp152.3.21.1
openSUSE:Leap 15.2	nodejs14	before 14.18.1-lp152.17.1	14.18.1-lp152.17.1
openSUSE:Leap 15.3	nodejs12	before 12.22.7-4.22.1	12.22.7-4.22.1
openSUSE:Leap 15.3	nodejs14	before 14.18.1-15.21.2	14.18.1-15.21.2
SUSE:Linux Enterprise Module for Web and Scripting 12	nodejs12	before 12.22.9-1.38.1	12.22.9-1.38.1
SUSE:Linux Enterprise Module for Web and Scripting 12	nodejs14	before 14.18.1-6.18.2	14.18.1-6.18.2
SUSE:Linux Enterprise Module for Web and Scripting 15 SP2	nodejs12	before 12.22.7-4.22.1	12.22.7-4.22.1
SUSE:Linux Enterprise Module for Web and Scripting 15 SP2	nodejs14	before 14.18.1-15.21.2	14.18.1-15.21.2

Same product

npmjs: all records

Other highest-scoring records for the same primary product.

CVE-2021-39135UNIX Symbolic Link (Symlink) Following in @npmcli/arborist
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
alpine:nodejs	12.22.6-r0 · Alpine:v3.11	Package registry (OSV)
debian:npm	7.24.0+ds-2 · Debian:12	Package registry (OSV)
npm:@npmcli/arborist	2.8.2	Package registry (OSV)
opensuse:nodejs12	12.22.7-lp152.3.21.1 · openSUSE:Leap 15.2	Package registry (OSV)
opensuse:nodejs14	14.18.1-lp152.17.1 · openSUSE:Leap 15.2	Package registry (OSV)
suse:nodejs12	12.22.7-4.22.1 · SUSE:Linux Enterprise Module for Web and Scripting 15 SP2	Package registry (OSV)
suse:nodejs14	14.18.1-6.18.2 · SUSE:Linux Enterprise Module for Web and Scripting 12	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

No history yet (it accumulates with the daily EPSS job).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

No commit or PR link among the references.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).