Timing-based IAM Username Enumeration in AWS Sign-In Flow
CVE-2025-0693 Published on January 23, 2025

Issue with AWS Sign-in IAM User Login Flow - Possible Username Enumeration
Variable response times in the AWS Sign-in IAM user login flow allowed for the use of brute force enumeration techniques to identify valid IAM usernames in an arbitrary AWS account.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2025-0693 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity and availability.

Attack Vector:
NETWORK
Attack Complexity:
LOW
Privileges Required:
NONE
User Interaction:
NONE
Scope:
UNCHANGED
Confidentiality Impact:
LOW
Integrity Impact:
NONE
Availability Impact:
NONE

Weakness Types

Observable Response Discrepancy

The product provides different responses to incoming requests in a way that reveals internal state information to an unauthorized actor outside of the intended control sphere. This issue frequently occurs during authentication, where a difference in failed-login messages could allow an attacker to determine if the username is valid or not. These exposures can be inadvertent (bug) or intentional (design).

Observable Timing Discrepancy

Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not. In security-relevant contexts, even small variations in timing can be exploited by attackers to indirectly infer certain details about the product's internal operations. For example, in some cryptographic algorithms, attackers can use timing differences to infer certain properties about a private key, making the key easier to guess. Timing discrepancies effectively form a timing side channel.


Products Associated with CVE-2025-0693

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Amazon Aws
 

Affected Versions

AWS Sign-in IAM Login Flow Version N/A is affected by CVE-2025-0693

Exploit Probability

EPSS
0.15%
Percentile
35.45%

EPSS (Exploit Prediction Scoring System) scores estimate the probability that a vulnerability will be exploited in the wild within the next 30 days. The percentile shows you how this score compares to all other vulnerabilities.