CVE-2026-21620Network attack vector

Remote file access via unchecked TFTP paths

Published Feb 20, 2026 · Updated Feb 20, 2026

Path traversal in Erlang/OTP TFTP allows remote attackers to read or write files outside a configured root directory. The tftp_file callback concatenates an untrusted request filename with root_dir without rejecting ../ components, allowing the resolved path to escape that directory. Exposure requires a reachable TFTP server using tftp_file with root_dir; access is limited to files readable or writable by the Erlang VM account.

CVSS severity2.3
Low
EPSS probability0.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in Erlang/OTP TFTP allows remote attackers to read or write files outside a configured root directory. The tftp_file callback concatenates an untrusted request filename with root_dir without rejecting ../ components, allowing the resolved path to escape that directory. Exposure requires a reachable TFTP server using tftp_file with root_dir; access is limited to files readable or writable by the Erlang VM account.

The record

CVE
CVE-2026-21620
Published
Feb 20, 2026
Updated
Feb 20, 2026
Vendor
Erlang
Product
Erlang/OTP
Classifications
CWE-23, CAPEC-139, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=07b8f441ca711f9812fad9e9115bab3c3aa92f79 <* changes=[{"at":"655fb95725ba2fb811740b57e106873833824344","status":"unaffected"},{"at":"3970738f687325138eb75f798054fa8960ac354e","status":"unaffected"},{"at":"696fdec922661d4a3cc528fc34bc24fae8d4ad8a","status":"unaffected"}]
  2. Affected versionversion=1.0 <* changes=[{"at":"1.1.1.1","status":"unaffected"},{"at":"1.2.2.1","status":"unaffected"},{"at":"1.2.4","status":"unaffected"}]
  3. Affected versionversion=17.0 <* changes=[{"at":"26.2.5.17","status":"unaffected"},{"at":"27.3.4.8","status":"unaffected"},{"at":"28.3.2","status":"unaffected"}]
  4. Affected versionversion=5.10 <7.0
  5. Affected versionversion=pkg:otp/[email protected] <pkg:otp/[email protected]
  6. Affected versionversion=pkg:otp/[email protected] <pkg:otp/tftp@* changes=[{"at":"pkg:otp/[email protected]","status":"unaffected"},{"at":"pkg:otp/[email protected]","status":"unaffected"},{"at":"pkg:otp/[email protected]","status":"unaffected"}]

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Erlang · Erlang/OTPversion=07b8f441ca711f9812fad9e9115bab3c3aa92f79 <* changes=[{"at":"655fb95725ba2fb811740b57e106873833824344","status":"unaffected"},{"at":"3970738f687325138eb75f798054fa8960ac354e","status":"unaffected"},{"at":"696fdec922661d4a3cc528fc34bc24fae8d4ad8a","status":"unaffected"}]; version=1.0 <* changes=[{"at":"1.1.1.1","status":"unaffected"},{"at":"1.2.2.1","status":"unaffected"},{"at":"1.2.4","status":"unaffected"}]; version=17.0 <* changes=[{"at":"26.2.5.17","status":"unaffected"},{"at":"27.3.4.8","status":"unaffected"},{"at":"28.3.2","status":"unaffected"}]; version=5.10 <7.0; version=pkg:otp/[email protected] <pkg:otp/[email protected]; version=pkg:otp/[email protected] <pkg:otp/tftp@* changes=[{"at":"pkg:otp/[email protected]","status":"unaffected"},{"at":"pkg:otp/[email protected]","status":"unaffected"},{"at":"pkg:otp/[email protected]","status":"unaffected"}]

Published CVSS scores

2.3Erlang Ecosystem FoundationCVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-23Relative Path Traversal
CAPEC-139Relative Path Traversal
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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