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Vulnerabilities

Vulnerability · CVE-2025-43857

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby.

Published Apr 28, 2025 · catalog updated Apr 28, 2025 · Ruby

Check if you run it

No confirmed exploitation is on record for CVE-2025-43857. EPSS is 0.49%. Act only if a listed version of Ruby is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Medium6.0
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.49%
Remediation
Version ranges on file
Affected products
vendor Ruby net-imap 0, < 0.2.5

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 you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • vendor Ruby net-imap 0, < 0.2.50, < 0.2.5

How to fix CVE-2025-43857

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2025-43857. EPSS is 0.49%. Act only if a listed version of Ruby is installed.

Which versions are affected?

Compare what you have installed with Ruby net-imap 0, < 0.2.5 0, < 0.2.5. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.49%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 28, 2025 · EUVD

    Detected

    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 receiv

  2. Apr 28, 2025 · EUVD

    Updated

    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 receiv

Sources

  • CVE.orgVulnerability recordCVE-2025-43857

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2025-43857

    30-day exploitation probability 0.5%

    first.org
  • EUVDVulnerability recordEUVD-2025-12559

    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 co

    euvd.enisa.europa.eu

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.