CVE-2026-42257

5.8 MEDIUM 0.4% exploit odds Fix listed Injection Server

What it is

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this string is derived from user-controlled input, it may contain contain CRLF sequences, which an attacker can use to inject arbitrary IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

At a glance

Exploitability: Can be exploited locally on the machine without logging in, but needs a user to act. High risk of data tampering.
Exploit odds: 0.4% chance of exploitation in the next 30 days (EPSS).
Fix: A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

2026-05-09 20:16 UTC PublishedDisclosed publicly on CVE.org and NVD
2026-07-24 21:10 UTC Last updatedMost recent change to the record

Why it ranks here

Exploited in the wild: no, CISA does not list it.
Exploit odds: 0.4% in the next 30 days (EPSS).
Severity: 5.8 MEDIUM (CVSS).
Fix: a patch or advisory is linked.

Details

Published: 2026-05-09 20:16 UTC
Last modified: 2026-07-24 21:10 UTC
Exploit probability: 0.4% · EPSS, next 30 days
Weakness: CWE-77 · Command injection
Record status: Analyzed

Affected

ruby-lang net\ < 0.4.24
ruby-lang net\ < 0.5.14
ruby-lang net\ < 0.6.4

Attack profile CVSS 4.0 · 5.8

Attack vector: Local
Complexity: Low
Attack requirements: Present
Privileges needed: None
User interaction: Passive
Confidentiality: None
Integrity: High
Availability: Low

Raw vector

CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2026-42257.md and follow it. Check whether this project is affected by CVE-2026-42257. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

· More options · Status badge

Download Square Reddit

Fix and advisories

References

NVD record · CVE.org record