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KEX init error results with excessive memory usage

High
u3s published GHSA-vvr3-fjhh-cfwc Mar 28, 2025

Package

No package listed

Affected versions

< OTP-27.3.1
< OTP-26.2.5.10
< OTP-25.3.2.19

Patched versions

OTP-27.3.1
OTP-26.2.5.10
OTP-25.3.2.19

Description

Impact

Maliciously formed KEX init message can result with high memory usage.
Implementation does not verify RFC specified limits on algorithm names (64 characters) provided in KEX init message.

Big KEX init packet may lead to inefficient processing of the error data. As a result, large amount of memory will be allocated for processing malicious data.

Patches

  • OTP-27.3.1
  • OTP-26.2.5.10
  • OTP-25.3.2.19

Workarounds

  • set option parallel_login to false
  • reduce max_sessions option

References

n/a

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
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
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:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVE ID

CVE-2025-30211

Weaknesses