net-imap up to 0.2.4/0.3.8/0.4.19/0.5.6 on Ruby Response Net::IMAP resource consumption

Summaryinfo

A vulnerability has been found in net-imap up to 0.2.4/0.3.8/0.4.19/0.5.6 on Ruby and classified as problematic. Impacted is the function Net::IMAP of the component Response Handler. This manipulation causes resource consumption. This vulnerability is handled as CVE-2025-43857. The attack can be initiated remotely. There is not any exploit available. The affected component should be upgraded.

Detailsinfo

A vulnerability was found in net-imap up to 0.2.4/0.3.8/0.4.19/0.5.6 on Ruby. It has been declared as problematic. Affected by this vulnerability is the function Net::IMAP of the component Response Handler. The manipulation with an unknown input leads to a resource consumption vulnerability. The CWE definition for the vulnerability is CWE-400. The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources. As an impact it is known to affect availability. The summary by CVE is:

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.5.7, 0.4.20, 0.3.9, and 0.2.5, there is a possibility for denial of service by memory exhaustion when net-imap reads server responses. At any time while the client is connected, a malicious server can send can send a "literal" byte count, which is automatically read by the client's receiver thread. The response reader immediately allocates memory for the number of bytes indicated by the server response. This should not be an issue when securely connecting to trusted IMAP servers that are well-behaved. It can affect insecure connections and buggy, untrusted, or compromised servers (for example, connecting to a user supplied hostname). This issue has been patched in versions 0.5.7, 0.4.20, 0.3.9, and 0.2.5.

The advisory is shared at github.com. This vulnerability is known as CVE-2025-43857 since 04/17/2025. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details are known, but no exploit is available. MITRE ATT&CK project uses the attack technique T1499 for this issue.

The vulnerability scanner Nessus provides a plugin with the ID 249200 (EulerOS 2.0 SP11 : ruby (EulerOS-SA-2025-1967)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 0.2.5, 0.3.9, 0.4.20 or 0.5.7 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (249200) and EUVD (EUVD-2025-12559). If you want to get the best quality for vulnerability data then you always have to consider VulDB.

Productinfo

Type

• Ruby Gem

Name

• net-imap

Version

• 0.2.0
• 0.2.1
• 0.2.2
• 0.2.3
• 0.2.4
• 0.3.0
• 0.3.1
• 0.3.2
• 0.3.3
• 0.3.4
• 0.3.5
• 0.3.6
• 0.3.7
• 0.3.8
• 0.4.0
• 0.4.1
• 0.4.2
• 0.4.3
• 0.4.4
• 0.4.5
• 0.4.6
• 0.4.7
• 0.4.8
• 0.4.9
• 0.4.10
• 0.4.11
• 0.4.12
• 0.4.13
• 0.4.14
• 0.4.15
• 0.4.16
• 0.4.17
• 0.4.18
• 0.4.19
• 0.5.0
• 0.5.1
• 0.5.2
• 0.5.3
• 0.5.4
• 0.5.5
• 0.5.6

CPE 2.3info

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CPE 2.2info

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If you want to get the best quality for vulnerability data then you always have to consider VulDB.

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