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CVE-2026-42257

📛 CVE Title

net-imap: Command Injection via "raw" arguments to multiple commands

⬇ Download JSON ⚠ View as Threat

Description

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.

Overview

State
PUBLISHED
Assigner (CNA)
GitHub_M
CVSS severity
MEDIUM
CVSS score
CVSS 5.8 / 10 5.8 5.8 / 10
CVSS 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
Effective score
5.8 / 10 MEDIUM source: CNA overview
CWE(s)
CWE-93, CWE-77
Reserved
2026-04-26
Published
2026-05-09 21:39 UTC
Last updated
2026-05-13 21:33 UTC
Source
https://raw.githubusercontent.com/CVEProject/cvelistV5/main/cves/2026/42xxx/CVE-2026-42257.json
Linked Threat
CVE-2026-42257 — CVE-2026-42257

NVD triage scoring NVD CVE 2.0

Layer NVD adds on top of the CNA's CVE record — published / last-modified timestamps, exploitability / impact subscores, and the FIRST.org EPSS probability that this CVE will be exploited in the wild in the next 30 days.

NVD published
2026-05-09 20:16:28 UTC
NVD last modified
2026-05-18 17:59:37 UTC
NVD CVSS v3.1
CVSS 9.8 / 10 9.8 9.8 / 10 CRITICAL source: nvd@nist.gov
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploitability subscore
3.9 / 10
Impact subscore
5.9 / 10
EPSS score
0.0002 (probability of exploitation in next 30 days)
EPSS percentile
3.87% vs all CVEs — higher = more likely to be exploited, as of 2026-05-24

NVD / KEV / EPSS data refreshed 2026-05-25 09:36 UTC. Re-run the 🛰 Backfill from NVD button above to refresh.

European Union Vulnerability Database ENISA EUVD

ENISA's official EU repository for curated vulnerability intelligence. Carries a separate identifier (EUVD-YYYY-NNNN) and frequently exposes an earlier-published description + CVSS than NVD does.

EUVD ID
EUVD-2026-28926
Assigner
GitHub_M
Published
May 9, 2026, 7:39:48 PM
Updated
May 13, 2026, 7:33:13 PM
EUVD base score (CVSS 4.0)
5.8 / 10
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
EUVD-reported EPSS
0.0200
Vendors
Ruby
Products
net-imap (0.5.0, < 0.5.14)
net-imap (< 0.4.24)
net-imap (0.6.0, < 0.6.4)
Aliases
GHSA-hm49-wcqc-g2xg

ENISA description: 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.

EUVD references (4)

Microsoft Security Response Center MSRC

Microsoft's vendor-authoritative record from the Security Update Guide — its own CVSS score, impact, severity rating, exploit assessment, and KB-article fixes. Refreshed 2026-08-12 01:09 UTC (source: CVRF).

MS severity
Moderate
Release
2026-May

Affected products (1)
VendorProductVersionsPlatforms
ruby net-imap < 0.4.24 (affected), >= 0.5.0, < 0.5.14 (affected), >= 0.6.0, < 0.6.4 (affected) —

Affected products — CPE 2.3 (1) NVD

NVD's normalized CPE 2.3 matchers, used by vendor tools (vulnerability scanners, asset managers) for automated detection. Compare with the CNA's free-text "Affected products" section above.

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

Vendor references (4)

References embedded in the original CVE record by the assigning CNA.

MITRE references (4) cveawg.mitre.org

Pulled from MITRE's CVE Services API by the 🛰 Backfill from MITRE button.

Web references (4)

DuckDuckGo results ranked by threat-intel / vendor advisory domains. Generated by the 🔎 Find references (web) button above — same flow as the Remediations search.

NVD-tagged references (4)

Reference list NVD curates from the CNA record, vendor advisories, and third-party reports. The tag chips below are NVD's analyst-assigned categories.

Remediations (15)

Remediations are stored against the linked Threat row; the list below is deduplicated across both pages.

  • Windows Kerberos RC4 deprecation: what will break in Active ... - 4sysops
    web:4sysops.com

    Starting in April 2026 , Windows updates will change the default Kerberos ticket issuance behavior to AES-SHA1 for accounts without explicit encryption settings, while RC4 can still be used where explicitly enabled. This change, driven by CVE - 2026 -20833, affects every Windows Server environment where service accounts or devices still rely on RC4. Any service account, NAS device, or legacy ...

    2026-05-23 21:03 UTC
  • NVD - cve-2026-42257
    web:nvd.nist.gov

    An official website of the United States government Here's how you know

    2026-05-23 21:03 UTC
  • March 13, 2026—Hotpatch KB5084597 (OS Builds 26200.7982 and 26100.7982 ...
    web:support.microsoft.com

    This update for Windows 11, version 25H2 and 24H2 (KB5084597) incudes security improvements. To learn more about differences between security updates, optional non-security preview updates, out-of-band (OOB) updates, and continuous innovation, see Windows monthly updates explained. For information on Windows update terminology, see the different types of Windows software updates. To view the ...

    2026-05-23 21:03 UTC
  • Microsoft says hackers are exploiting critical zero-day ... - TechCrunch
    web:techcrunch.com

    Critical security flaws targeting Windows and Office users allow hackers to take complete control of a victim's computer by clicking a malicious link or opening a file. Patch now.

    2026-05-23 21:03 UTC
  • Microsoft releases Windows 11 OOB hotpatch to fix RRAS RCE flaw
    web:www.bleepingcomputer.com

    Microsoft has released an out-of-band (OOB) update to fix a security vulnerabilities affecting Windows 11 Enterprise devices that receive hotpatch updates instead of the regular Patch Tuesday ...

    2026-05-23 21:03 UTC
  • Critical Patches Issued for Microsoft Products, May 12, 2026
    web:www.cisecurity.org

    <p>Multiple vulnerabilities have been discovered in Microsoft products, the most severe of which could allow for remote code execution. Successful exploitation of the most severe of these vulnerabilities could result in an attacker gaining the same privileges as the logged-on user. Depending on the privileges associated with the user, an attacker could then install programs; view, change, or ...

    2026-05-23 21:03 UTC
  • February's Patch Tuesday release fixes 59 flaws ... - Computerworld
    web:www.computerworld.com

    Each month, the team at Readiness analyzes the latest Patch Tuesday updates from Microsoft and provides detailed, actionable testing guidance. The company's Patch Tuesday release for February ...

    2026-05-23 21:03 UTC
  • 'Reboot Your PC'—Microsoft Changes 'Most Windows Devices' In June
    web:www.forbes.com

    Microsoft starts expiring critical Secure Boot certificates in just 2 weeks.

    2026-05-23 21:03 UTC
  • Microsoft fixes 167 security flaws in April, second biggest Patch ...
    web:www.pcworld.com

    This month's Patch Tuesday includes an actively exploited Office zero-day vulnerability and several critical RCE bugs in Windows and Remote Desktop.

    2026-05-23 21:03 UTC
  • Microsoft Issues Massive Windows Patch for 160+ Bugs ... - TechRepublic
    web:www.techrepublic.com

    Microsoft's April 2026 Patch Tuesday fixes 165 vulnerabilities, including two zero-days, in one of the company's largest monthly security updates.

    2026-05-23 21:03 UTC
  • Microsoft Patch Tuesday February 2026 - 54 Vulnerabilities Fixed ...
    web:cybersecuritynews.com

    Microsoft released its February 2026 Patch Tuesday updates on February 10, addressing 54 vulnerabilities, including six zero-days across Windows, Office, Azure, and developer tools.

    2026-05-26 02:49 UTC
  • Microsoft releases emergency updates to fix Windows Server issues
    web:www.bleepingcomputer.com

    Microsoft has released out-of-band (OOB) updates to fix issues affecting Windows Server systems after installing the April 2026 security updates.

    2026-05-26 02:49 UTC
  • Microsoft Releases Out-of-Band Security Update to Mitigate ... - CISA
    web:www.cisa.gov

    Updated October 29, 2025: CISA has updated this Alert to include revised information on vulnerable product identification, potential threat activity detections, and additional resources. Microsoft released an update to address a critical remote code execution vulnerability impacting Windows Server Update Service (WSUS) in Windows Server (2012, 2016, 2019, 2022, and 2025), CVE -2025-59287

    2026-05-26 02:49 UTC
  • CVE: Common Vulnerabilities and Exposures
    web:www.cve.org

    At cve .org, we provide the authoritative reference method for publicly known information-security vulnerabilities and exposures

    2026-05-26 02:49 UTC
  • Patch Tuesday May 2026: Security Updates & CVE Analysis
    web:zecurit.com

    Get the complete breakdown of Microsoft's May 2026 Patch Tuesday. We analyze the latest security updates and all critical CVEs .

    2026-05-26 02:49 UTC

AI Forensic Analysis

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Raw JSON

The full cvelistV5 record. Download as CVE-2026-42257.json.

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