CVE-2024-37358: Apache James Server DoS Vulnerability

CVE-2024-37358 Overview

CVE-2024-37358 is a denial of service vulnerability in Apache James Server. The flaw allows both authenticated and unauthenticated users to abuse IMAP literals to trigger unbounded memory allocation and very long computations. The issue resembles CVE-2024-34055 and stems from insufficient resource limits on protocol input. Apache James versions 3.7.6 and 3.8.2 restrict the illegitimate use of IMAP literals. The vulnerability is tracked under CWE-770: Allocation of Resources Without Limits or Throttling.

Critical Impact
Remote unauthenticated attackers can exhaust server memory and CPU, rendering Apache James mail services unavailable to legitimate users.

Affected Products

Apache James Server versions prior to 3.7.6
Apache James Server versions prior to 3.8.2 in the 3.8.x branch
Deployments exposing the IMAP service to network clients

Discovery Timeline

2025-02-06 - CVE-2024-37358 published to NVD
2025-09-29 - Last updated in NVD database

Technical Details for CVE-2024-37358

Vulnerability Analysis

Apache James implements the Internet Message Access Protocol (IMAP), which supports literal syntax for transmitting binary or large payloads. A literal is announced by the client with a byte count in braces, for example {1048576}, followed by that many octets of data. The server allocates buffers to receive the announced payload before any authentication or command validation completes.

The vulnerability exists because the server does not enforce strict upper bounds on the size or repetition of these literal declarations. An attacker can supply oversized literal length values or chain many literal continuations within a single command stream. The result is excessive memory allocation and prolonged parsing computations that consume server resources.

Because the IMAP greeting and pre-authentication command set accept literals, exploitation does not require valid credentials. The attack vector is the network, complexity is low, and only availability is affected. This aligns with the issue type described in [CWE-770].

Root Cause

The root cause is missing validation of client-supplied length values in IMAP literal parsing. Apache James trusted the announced literal size and allocated buffers accordingly, without comparing against a configurable maximum. The fix in versions 3.7.6 and 3.8.2 introduces limits that reject oversized or abusive literal usage before resources are committed.

Attack Vector

An attacker connects to a network-reachable IMAP port and issues commands that contain literal declarations with very large byte counts. Repeating this pattern across concurrent connections multiplies the effect. Memory allocation grows unbounded and CPU time spent parsing input rises until the Java Virtual Machine runs out of heap or stops servicing legitimate traffic.

No verified exploit code is published for CVE-2024-37358. Refer to the Apache Security Mailing List Thread for the upstream discussion.

Detection Methods for CVE-2024-37358

Indicators of Compromise

Sudden spikes in Java heap usage or OutOfMemoryError events in Apache James logs
IMAP connections that send unusually large literal length values such as {99999999} before authentication
Sustained high CPU utilization on the James process correlated with inbound IMAP traffic
Mail clients reporting timeouts or disconnections from the IMAP service

Detection Strategies

Inspect IMAP traffic with network monitoring tools and flag commands that contain literal byte counts exceeding reasonable thresholds for mail operations
Correlate Apache James JVM metrics with connection counts to identify resource exhaustion patterns
Run version inventory queries against mail infrastructure to surface hosts running Apache James prior to 3.7.6 or 3.8.2

Monitoring Recommendations

Enable detailed IMAP protocol logging and forward events to a centralized analytics platform for baseline analysis
Alert on repeated connection drops, JVM garbage collection pressure, and java.lang.OutOfMemoryError stack traces
Track the ratio of pre-authentication command volume to successful logins per source address

How to Mitigate CVE-2024-37358

Immediate Actions Required

Upgrade Apache James Server to version 3.7.6, 3.8.2, or later
Restrict IMAP service exposure to trusted network segments where business requirements allow
Apply rate limiting and connection caps at the network perimeter to reduce abuse potential
Review JVM heap configuration and set bounded memory limits so a single process cannot exhaust host resources

Patch Information

The Apache James project addressed CVE-2024-37358 in releases 3.7.6 and 3.8.2. These versions enforce limits on IMAP literal usage and reject requests that would trigger unbounded allocation. Patch details and release notes are available through the Apache Security Mailing List Thread.

Workarounds

Place a reverse proxy or IMAP-aware gateway in front of Apache James to enforce request size limits
Use firewall rules to restrict IMAP access to known client networks until patching is complete
Configure operating system resource limits on the James service account to contain memory consumption

bash

# Verify the installed Apache James version and upgrade path
java -jar james-server-app.jar --version
# Replace the binary with a patched release
wget https://downloads.apache.org/james/server/3.8.2/james-server-app-3.8.2-app.zip
systemctl restart james