NVD / CVE Program· CNA GitHub_M

CVE-2021-37701: Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning using symbolic links

Noroxi assessment

Priority: Monitor (action score 35/100)

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: 3.2% (FIRST EPSS); higher than 88.4% of all records.
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 (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+2618+8d46dafd, 1:14.18.2-2.module_el8.5.0+254+b4526b16; nodejs-devel (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+254+b4526b16, 1:14.18.2-2.module_el8.5.0+2618+8d46dafd; nodejs-docs (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+254+b4526b16, 1:14.18.2-2.module_el8.5.0+2618+8d46dafd.
Mentioned 2 times in Turkish national cyber security advisories (siberguvenlik.gov.tr).

Low priority for now. Upgrade to nodejs (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+2618+8d46dafd, 1:14.18.2-2.module_el8.5.0+254+b4526b16; nodejs-devel (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+254+b4526b16, 1:14.18.2-2.module_el8.5.0+2618+8d46dafd; nodejs-docs (AlmaLinux:8) 1:14.18.2-2.module_el8.5.0+254+b4526b16, 1:14.18.2-2.module_el8.5.0+2618+8d46dafd 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

The npm package "tar" (aka node-tar) before versions 4.4.16, 5.0.8, and 6.1.7 has an arbitrary file creation/overwrite and arbitrary code execution vulnerability. node-tar aims to guarantee that any file whose location would be modified by a symbolic link is not extracted. This is, in part, achieved by ensuring that extracted directories are not symlinks. Additionally, in order to prevent unnecessary stat calls to determine whether a given path is a directory, paths are cached when directories are created. This logic was insufficient when extracting tar files that contained both a directory and a symlink with the same name as the directory, where the symlink and directory names in the archive entry used backslashes as a path separator on posix systems. The cache checking logic used both `\` and `/` characters as path separators, however `\` is a valid filename character on posix systems. By first creating a directory, and then replacing that directory with a symlink, it was thus possible to bypass node-tar symlink checks on directories, essentially allowing an untrusted tar file to symlink into an arbitrary location and subsequently extracting arbitrary files into that location, thus allowing arbitrary file creation and overwrite. Additionally, a similar confusion could arise on case-insensitive filesystems. If a tar archive contained a directory at `FOO`, followed by a symbolic link named `foo`, then on case-insensitive file systems, the creation of the symbolic link would remove the directory from the filesystem, but _not_ from the internal directory cache, as it would not be treated as a cache hit. A subsequent file entry within the `FOO` directory would then be placed in the target of the symbolic link, thinking that the directory had already been created. These issues were addressed in releases 4.4.16, 5.0.8 and 6.1.7. The v3 branch of node-tar has been deprecated and did not receive patches for these issues. If you are still using a v3 release we recommend you update to a more recent version of node-tar. If this is not possible, a workaround is available in the referenced GHSA-9r2w-394v-53qc.

HighCVSS 8.6 · v3.1—No exploit Fix available

Published: Aug 31, 2021
Updated: Jun 17, 2026
EPSS: 3.2% · 88th percentile
CWE: CWE-22

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 34 / 40 · 8.6 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 1 / 30 · 3.2%

CNA vs NVD score

NVD: 8.6
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	tar	cpe:2.3:a:npmjs:tar
debian	debian linux	cpe:2.3:o:debian:debian_linux
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.

debian debian linux10.0
debian debian linux11.0
npmjs tar6.0.0 and later · before 6.1.7
npmjs tarbefore 4.4.16
npmjs tar5.0.0 and later · before 5.0.8
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 node-tar
- < 4.4.16, >= 5.0.0, < 5.0.8, >= 6.0.0, < 6.1.7affected

Package-level exposure

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

+72

Same product

npmjs: all records

Other highest-scoring records for the same primary product.

CVE-2021-37712Arbitrary File Creation/Overwrite via insufficient symlink protection due to directory cache poisoning using symbolic links
35Monitor
CVE-2021-37713Arbitrary File Creation/Overwrite on Windows via insufficient relative path sanitization
34Monitor

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
almalinux:nodejs	1:14.18.2-2.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
almalinux:nodejs-devel	1:14.18.2-2.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
almalinux:nodejs-docs	1:14.18.2-2.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
almalinux:nodejs-full-i18n	1:14.18.2-2.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
almalinux:nodejs-nodemon	2.0.15-1.module_el8.6.0+2904+f21ad6f4 · AlmaLinux:8	Package registry (OSV)
almalinux:nodejs-packaging	23-3.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
almalinux:npm	1:6.14.15-1.14.18.2.2.module_el8.5.0+2618+8d46dafd · AlmaLinux:8	Package registry (OSV)
alpine:nodejs	12.22.6-r0 · Alpine:v3.11	Package registry (OSV)
debian:node-tar	6.1.7+~cs11.3.10-1 · Debian:12	Package registry (OSV)
npm:tar	4.4.16	Package registry (OSV)
npm:tar	5.0.8	Package registry (OSV)
npm:tar	6.1.7	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)
red hat:nodejs	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-debuginfo	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-debugsource	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-devel	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-docs	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-full-i18n	1:12.22.12-1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-nodemon	0:1.18.3-1.module+el8.1.0+3369+37ae6a45 · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:nodejs-packaging	0:17-3.module+el8.1.0+3369+37ae6a45 · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:npm	1:6.14.16-1.12.22.12.1.module+el8.1.0+15296+87b2f6ad · Red Hat:rhel_e4s:8.1::appstream	Package registry (OSV)
red hat:rh-nodejs14-nodejs	0:14.18.2-1.el7 · Red Hat:rhel_software_collections:3::el7	Package registry (OSV)
red hat:rh-nodejs14-nodejs-debuginfo	0:14.18.2-1.el7 · Red Hat:rhel_software_collections:3::el7	Package registry (OSV)
red hat:rh-nodejs14-nodejs-devel	0:14.18.2-1.el7 · Red Hat:rhel_software_collections:3::el7	Package registry (OSV)
rocky linux:nodejs	1:14.18.2-2.module+el8.5.0+733+de4fee6c · Rocky Linux:8	Package registry (OSV)
rocky linux:nodejs-nodemon	0:2.0.15-1.module+el8.5.0+721+4c107270 · Rocky Linux:8	Package registry (OSV)
rocky linux:nodejs-packaging	0:23-3.module+el8.7.0+1071+4bdda2a8 · Rocky Linux:8	Package registry (OSV)
suse:nodejs12	12.22.7-4.22.1 · SUSE:Linux Enterprise Module for Web and Scripting 15 SP2	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.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

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).

National notice (Türkiye Cybersecurity Directorate / USOM)

Official security notices citing this record; remediation advice is on the agency's page.

TR-22-0615 · Sep 14, 2022(RedHat Güvenlik Güncellemesi)
TR-22-0215 · Mar 11, 2022(Siemens Güvenlik Bildirimi)

All national notices →

Technical details

Attack conditions

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.

If successful

Confidentiality: high · data can be read
Integrity: high · data or configuration can be modified
Availability: high · the service can be disrupted

Impact can extend beyond the vulnerable component (scope changes).

Attack vector: Local
Attack complexity: Low
Privileges required: None
User interaction: Required
Scope: Changed
Confidentiality impact: High
Integrity impact: High
Availability impact: High

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

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

nvd-primary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1const file = path.join(ROOT, req.query.name);
2res.sendFile(file);

Fixed

1const file = path.resolve(ROOT, req.query.name);
2if (!file.startsWith(ROOT + path.sep)) {
3  return res.sendStatus(400);
4}
5res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Sep 28, 2026, 10:47 PM UTC

For records you follow, these changes also arrive as notifications. →

References

cert-portal.siemens.com/productcert/pdf/ssa-389290.pdf

Show all references (5 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records

Ecosystem	Package	Affected range	Fix
AlmaLinux:8	nodejs	before 1:14.18.2-2.module_el8.5.0+2618+8d46dafd	1:14.18.2-2.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	nodejs	before 1:14.18.2-2.module_el8.5.0+254+b4526b16	1:14.18.2-2.module_el8.5.0+254+b4526b16
AlmaLinux:8	nodejs-devel	before 1:14.18.2-2.module_el8.5.0+254+b4526b16	1:14.18.2-2.module_el8.5.0+254+b4526b16
AlmaLinux:8	nodejs-devel	before 1:14.18.2-2.module_el8.5.0+2618+8d46dafd	1:14.18.2-2.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	nodejs-docs	before 1:14.18.2-2.module_el8.5.0+254+b4526b16	1:14.18.2-2.module_el8.5.0+254+b4526b16
AlmaLinux:8	nodejs-docs	before 1:14.18.2-2.module_el8.5.0+2618+8d46dafd	1:14.18.2-2.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	nodejs-full-i18n	before 1:14.18.2-2.module_el8.5.0+254+b4526b16	1:14.18.2-2.module_el8.5.0+254+b4526b16
AlmaLinux:8	nodejs-full-i18n	before 1:14.18.2-2.module_el8.5.0+2618+8d46dafd	1:14.18.2-2.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	nodejs-nodemon	before 2.0.15-1.module_el8.6.0+2904+f21ad6f4	2.0.15-1.module_el8.6.0+2904+f21ad6f4
AlmaLinux:8	nodejs-nodemon	before 2.0.15-1.module_el8.5.0+2618+8d46dafd	2.0.15-1.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	nodejs-nodemon	before 2.0.15-1.module_el8.5.0+2605+45d748af	2.0.15-1.module_el8.5.0+2605+45d748af
AlmaLinux:8	nodejs-packaging	before 23-3.module_el8.4.0+2522+3bd42762	23-3.module_el8.4.0+2522+3bd42762
AlmaLinux:8	nodejs-packaging	before 23-3.module_el8.5.0+2618+8d46dafd	23-3.module_el8.5.0+2618+8d46dafd
AlmaLinux:8	npm	before 1:6.14.15-1.14.18.2.2.module_el8.5.0+254+b4526b16	1:6.14.15-1.14.18.2.2.module_el8.5.0+254+b4526b16
AlmaLinux:8	npm	before 1:6.14.15-1.14.18.2.2.module_el8.5.0+2618+8d46dafd	1:6.14.15-1.14.18.2.2.module_el8.5.0+2618+8d46dafd
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:10	node-tar	before 4.4.6+ds1-3+deb10u2	4.4.6+ds1-3+deb10u2
Debian:11	node-tar	before 6.0.5+ds1+~cs11.3.9-1+deb11u2	6.0.5+ds1+~cs11.3.9-1+deb11u2
Debian:12	node-tar	before 6.1.7+~cs11.3.10-1	6.1.7+~cs11.3.10-1
npm	tar	from 3.0.0 · before 4.4.16	4.4.16
npm	tar	from 5.0.0 · before 5.0.8	5.0.8
npm	tar	from 6.0.0 · before 6.1.7	6.1.7
openSUSE:Leap 15.2	nodejs12	before 12.22.7-lp152.3.21.1	12.22.7-lp152.3.21.1