https://vulnerability.circl.lu/rss/recent/all/10 Most recent entries from all 2026-09-29T15:59:28.852693+00:00 Vulnerability-Lookup info@circl.lu python-feedgen Contains only the most 10 recent entries. https://vulnerability.circl.lu/vuln/cve-2025-43857 CVE-2025-43857 — net-imap rubygem vulnerable to possible DoS by memory exhaustion 2026-09-29T15:59:29.558474+00:00

Affected: ruby net-imap

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.

 https://vulnerability.circl.lu/vuln/ghsa-j3g3-5qv5-52mj GHSA-j3g3-5qv5-52mj — net-imap rubygem vulnerable to possible DoS by memory exhaustion 2026-09-29T15:59:29.558662+00:00

Affected: RubyGems: net-imap

### Summary

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).

### Details

The IMAP protocol allows "literal" strings to be sent in responses, prefixed with their size in curly braces (e.g. `{1234567890}\r\n`). When `Net::IMAP` receives a response containing a literal string, it calls `IO#read` with that size. When called with a size, `IO#read` immediately allocates memory to buffer the entire string before processing continues. The server does not need to send any more data. There is no limit on the size of literals that will be accepted.

### Fix #### Upgrade Users should upgrade to `net-imap` 0.5.7 or later. A configurable `max_response_size` limit has been added to `Net::IMAP`'s response reader. The `max_response_size` limit has also been backported to `net-imap` 0.2.5, 0.3.9, and 0.4.20.

To set a global value for `max_response_size`, users must upgrade to `net-imap` ~> 0.4.20, or > 0.5.7.

#### Configurat…