Net CVE-2025-43857

MEDIUM

Uncontrolled Resource Consumption (CWE-400)

2025-04-28 security-advisories@github.com

Denial Of Service Red Hat Suse Net Ruby Lang

6.0

CVSS 4.0 · GitHub Advisory

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Vulnerability Assessment

Weakness	CWE CWE-400 OWASP Top 10:2025 A06:2025 - Insecure Design ASVS 5.0 V2 - Validation and Business Logic Resource consumption limits MITRE ATT&CK 1 technique across 1 tactic: Impact The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 6.0 (MEDIUM). Attack characteristics: network attack vector, low complexity, no privileges required, user interaction required. EPSS exploitation probability: 0.53%.
Exploit ScenarioDerived	A remote attacker could cause denial of service by exhausting system resources by sending crafted requests to the affected application. No authentication is required to exploit this vulnerability.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).

Patch available 0.5% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 28, 2026

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Rated medium severity (CVSS 6.0), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Uncontrolled Resource Consumption vulnerability could allow attackers to cause denial of service by exhausting system resources.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Implement rate limiting, set resource quotas, validate input sizes, use timeouts.

Affected Packages

rubygems net-imap fix: 0.2.5, 0.3.9, 0.4.20, 0.5.7

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in rubygems

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

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Technical ContextAI · show details

This vulnerability is classified as Uncontrolled Resource Consumption (CWE-400), which allows attackers to cause denial of service by exhausting system resources. 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. Affected products include: Ruby-Lang Net\.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

GitHub Advisory PRIMARY 6.0 MEDIUM

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

SUSE 6.5 MEDIUM

AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

Red Hat 6.5 MEDIUM

Primary rating from GitHub Advisory.

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Attack Requirements

Present

Privileges Required

None

User Interaction

Passive

Vulnerable system: Confidentiality

None

Vulnerable system: Integrity

None

Vulnerable system: Availability

High

Subsequent system: Confidentiality

None

Subsequent system: Integrity

None

Subsequent system: Availability

None

Lifecycle Timeline

2

Patch released

Mar 28, 2026 - 18:39 nvd

Patch available

CVE Published

Apr 28, 2025 - 16:15 nvd

MEDIUM 6.0

DescriptionGitHub Advisory

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.

Executive ViewAI

Why It Matters

Organizations using Ruby. should be aware of moderate risk from CVE-2025-43857, a resource exhaustion vulnerability rated CVSS 6.0. Service availability could be impacted. A patch is available and should be applied during regular vulnerability management.

Business Impact: Low

Compensating Controls

Apply vendor patch. If patching is delayed: implement rate limiting and resource quotas.

Threat Intelligence Overview

EPSS Score

0.5%

Top 33% exploitable

Data Quality

4 sources

Confidence: Medium

CVE.org

EPSS Vendor

GitHub

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity MEDIUM

CISA KEV No

Public POC No

EPSS 0.5%

Patch available Yes

Active threat No

Deciding rule

MEDIUM severity (CVSS 4.0-6.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Defer

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

No

Human Impact

Low

Priority Score

31

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +30

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

Denial of Service MEDIUM

Denial of Service attacks render applications or systems unavailable by overwhelming resources or triggering failure conditions.

Affected Products (CPE)GitHub Advisory

cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

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Vendor StatusVendor

SUSE

Severity: Medium

Product	Status
SUSE Linux Enterprise Desktop 15 SP7	Fixed
SUSE Linux Enterprise Desktop 15 SP7	Fixed
SUSE Linux Enterprise High Availability Extension 15 SP7	Fixed
SUSE Linux Enterprise High Availability Extension 16.0	Fixed
SUSE Linux Enterprise High Availability Extension 16.1	Fixed

References

Advisories & patches

PATCH https://github.com/ruby/net-imap/pull/442 PATCH https://github.com/ruby/net-imap/pull/444/commits/0ae8576c1a90bcd9573f81bdad4b4b824642d105#diff-53721cb4d9c3fb86b95cc8476ca2df90968ad8c481645220c607034399151462 PATCH https://github.com/ruby/net-imap/pull/445 PATCH https://github.com/ruby/net-imap/pull/446 PATCH https://github.com/ruby/net-imap/pull/447 ADVISORY https://github.com/ruby/net-imap/security/advisories/GHSA-j3g3-5qv5-52mj

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