NVD / CVE Program· CNA EEF

CVE-2026-23942: SFTP root escape via component-agnostic prefix check in ssh_sftpd

Noroxi assessment

Priority: Monitor (action score 21/100)

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: 0.37% (FIRST EPSS).
Anyone who can reach it over the internet can trigger it. A low-privileged account is enough. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: Erlang OTP 26.2.5.18, 27.3.4.9, 27688a824f753d4c16371dc70e88753fb410590b; azl3 erlang 26.2.5.17-1 on Azure Linux 3.0 26.2.5.18-1; cbl2 erlang 25.3.2.21-4 on CBL Mariner 2.0 25.3.2.21-5.

Low priority for now. Upgrade to Erlang OTP 26.2.5.18, 27.3.4.9, 27688a824f753d4c16371dc70e88753fb410590b; azl3 erlang 26.2.5.17-1 on Azure Linux 3.0 26.2.5.18-1; cbl2 erlang 25.3.2.21-4 on CBL Mariner 2.0 25.3.2.21-5 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

Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') vulnerability in Erlang OTP (ssh_sftpd module) allows Path Traversal. This vulnerability is associated with program files lib/ssh/src/ssh_sftpd.erl and program routines ssh_sftpd:is_within_root/2. The SFTP server uses string prefix matching via lists:prefix/2 rather than proper path component validation when checking if a path is within the configured root directory. This allows authenticated users to access sibling directories that share a common name prefix with the configured root directory. For example, if root is set to /home/user1, paths like /home/user10 or /home/user1_backup would incorrectly be considered within the root. This issue affects OTP from OTP 17.0 before OTP 28.4.1, OTP 27.3.4.9 and OTP 26.2.5.18, corresponding to ssh from 3.0.1 before 5.5.1, 5.2.11.6 and 5.1.4.14.

MediumCVSS 5.3 · v4.0—No exploit Fix available

Path traversal

Published: Mar 13, 2026
Updated: Jul 24, 2026
EPSS: 0.3% · 31th percentile
CWE: CWE-22

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 21 / 40 · 5.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CISA SSVC decision

Exploitation: none
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · EEF: 5.3; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA: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

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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
erlang	erlang\/otp	cpe:2.3:a:erlang:erlang\/otp
erlang	erlang\/ssh	cpe:2.3:a:erlang:erlang\/ssh

Affected versions

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

erlang erlang/otp17.0 and later · before 26.2.5.18
erlang erlang/otp27.0 and later · before 27.3.4.9
erlang erlang/otp28.0 and later · before 28.4.1
erlang erlang/ssh3.0.1 and later · before 5.1.4.14
erlang erlang/ssh5.2 and later · before 5.2.11.6
erlang erlang/ssh5.5 and later · up to 5.5.1 inclusive

Versions reported by the vendor

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

Erlang OTP
- 3.0.1 and lateraffected · otpfixed in 5.5.1, 5.2.11.6, 5.1.4.14
- 17.0 and lateraffected · otpfixed in 28.4.1, 27.3.4.9, 26.2.5.18
- 84adefa331c4159d432d22840663c38f155cd4c1 and lateraffected · gitfixed in 27688a824f753d4c16371dc70e88753fb410590b, 9e0ac85d3485e7898e0da88a14be0ee2310a3b28, 5ed603a1211b83b8be2d1fc06d3f3bf30c3c9759

Package-level exposure

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

Ecosystem	Package	Affected range	Fix
Debian:12	erlang	before 1:25.2.3+dfsg-1+deb12u4	1:25.2.3+dfsg-1+deb12u4
Debian:13	erlang	before 1:27.3.4.1+dfsg-1+deb13u2	1:27.3.4.1+dfsg-1+deb13u2
Debian:14	erlang	before 1:27.3.4.9+dfsg-1	1:27.3.4.9+dfsg-1
openSUSE:Leap 16.0	erlang	before 27.1.3-160000.4.1	27.1.3-160000.4.1
openSUSE:Tumbleweed	erlang27	before 27.1.3-2.1	27.1.3-2.1

Same product

erlang: all records

Other highest-scoring records for the same primary product.

CVE-2025-32433Erlang/OTP SSH Vulnerable to Pre-Authentication RCEKEV
100Now
CVE-2017-1000385The Erlang otp TLS server answers with different TLS alerts to different error types in the RSA PKCS #1 1.5 padding.
60This week
CVE-2022-37026In Erlang/OTP before 23.3.4.15, 24.x before 24.3.4.2, and 25.x before 25.0.2, there is a Client Authentication Bypass in certain client-cert
39Monitor

Published before and after this one in the same product

← EarlierCVE-2020-35733Jan 15, 2021 · An issue was discovered in Erlang/OTP before 23.2.2.
30Monitor
← EarlierCVE-2021-29221Apr 9, 2021 · A local privilege escalation vulnerability was discovered in Erlang/OTP prior to version 23.2.3.
28Monitor
Later →CVE-2026-23943Mar 13, 2026 · Pre-auth SSH DoS via unbounded zlib inflate
27Monitor

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
Erlang OTP	26.2.5.18	Vendor (CNA)
Erlang OTP	27.3.4.9	Vendor (CNA)
Erlang OTP	27688a824f753d4c16371dc70e88753fb410590b	Vendor (CNA)
Erlang OTP	28.4.1	Vendor (CNA)
Erlang OTP	5.1.4.14	Vendor (CNA)
Erlang OTP	5.2.11.6	Vendor (CNA)
Erlang OTP	5.5.1	Vendor (CNA)
Erlang OTP	5ed603a1211b83b8be2d1fc06d3f3bf30c3c9759	Vendor (CNA)
Erlang OTP	9e0ac85d3485e7898e0da88a14be0ee2310a3b28	Vendor (CNA)
azl3 erlang 26.2.5.17-1 on Azure Linux 3.0	26.2.5.18-1 · CBL-Mariner Releases	Microsoft (MSRC)
cbl2 erlang 25.3.2.21-4 on CBL Mariner 2.0	25.3.2.21-5 · CBL-Mariner Releases	Microsoft (MSRC)
debian:erlang	1:25.2.3+dfsg-1+deb12u4 · Debian:12	Package registry (OSV)
opensuse:erlang	27.1.3-160000.4.1 · openSUSE:Leap 16.0	Package registry (OSV)
opensuse:erlang27	27.1.3-2.1 · openSUSE:Tumbleweed	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.

Credits

All researchers

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

Luigino Camastra / Aisle Researchfinder
Jakub Witczakremediation developer
Michał Wąsowskiremediation reviewer

Variant candidates

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

CVE-2026-3214739 days apartSFTP chroot bypass via path traversal in SSH_FXP_FSETSTAT
21Monitor

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).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
A low-privileged account is enough.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: Low
User interaction: None
Scope: X

Weakness class (CWE)

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

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

nvd-secondary

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, 10:11 PM UTC

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

References

cna.erlef.org/cves/CVE-2026-23942.html

Show all references (6 more)

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

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