APR-util <=1.6.3 Timing Leak via apr_password_validate
CVE-2025-49506 Published on August 6, 2026

Apache Portable Runtime Utility: apr_password_validate() vulnerable to timing attack
APR-util versions 1.6.3 (and earlier) function apr_password_validate() was not constant-time with regards to hashes or passwords comparisons, potentially leaking their content via a side channel timing attack particularly on platforms without crypt() such as  Windows, BeOS, NetWare, or Android. Users are recommended to upgrade to version 1.6.4, which fixes this issue.

Vendor Advisory NVD

Vulnerability Analysis

CVE-2025-49506 is exploitable 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 high impact on confidentiality, with no impact on integrity and availability.

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

Timeline

Reported to security team

fixed in 1.6.x by r1936805 794 days later.

1.6.4 released

Weakness Type

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.


Affected Versions

Apache Software Foundation Apache Portable Runtime Utility:

Exploit Probability

EPSS
0.39%
Percentile
32.25%

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.