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Erlang/OTP Windows Local Privilege Escalation via Unsafe Filesystem Permissions

High
IngelaAndin published GHSA-3rrc-f8wp-rx4j Jan 19, 2026

Package

OTP

Affected versions

>= 17.0

Patched versions

23.2.3
erts (OTP)
>= 6.0
11.1.7

Description

Impact

A local privilege escalation vulnerability was discovered in Erlang/OTP prior to version 23.2.3. By adding files to an existing installation's directory, a local attacker could hijack accounts of other users running Erlang programs or possibly coerce a service running with "erlsrv.exe" to execute arbitrary code as Local System. This can occur only under specific conditions on Windows with unsafe filesystem permissions.

Affected/Unaffected Versions

A version larger than or equal to one of the listed patched versions is unaffected; otherwise, a version that satisfies an expression listed under affected versions is affected, and if it does not, it is unaffected.

The documentation of the new OTP version scheme describes how versions should be compared. Note that versions used prior to OTP 17.0, when the new OTP version scheme was introduced, are never listed since it is not well defined how to compare those versions.

In the case of this vulnerability, versions prior to OTP 17.0 are likely also affected.

Credits

Thanks to DeepSurface Security, Inc. for finding and responsibly disclosing this vulnerability to the Erlang/OTP project.

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Local
Attack complexity
High
Privileges required
None
User interaction
Required
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H

CVE ID

CVE-2021-29221

Weaknesses

Untrusted Search Path

The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control. Learn more on MITRE.