Read the docs
TI-2025-28441 Aliases CVE-2025-43857GHSA-j3g3-5qv5-52mj

net-imap rubygem vulnerable to possible DoS by memory exhaustion

Priority LOW 27CWE-400Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
Present
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Partial Red Hat: 5 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-400.

Summary

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00494 42nd percentileScored 2026-11-07
Fix Partial net-imap (ruby): 0.5.7, 0.4.20, 0.3.9 +1net-imap (RubyGems): 0.5.7, 0.4.20, 0.3.9 +1Red Hat: 5 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
rubynet-imap0.5.0 to before 0.5.7; 0.4.0 to before 0.4.20; 0.3.0 to before 0.3.9; before 0.2.50.5.7, 0.4.20, 0.3.9, 0.2.5Patch availableCNA
—net-imap (RubyGems)0.5.0 to before 0.5.70.5.7Patch availableGHSA-j3g3-5qv5-52mj
—net-imap (RubyGems)0.4.0 to before 0.4.200.4.20Patch availableGHSA-j3g3-5qv5-52mj
—net-imap (RubyGems)0.3.0 to before 0.3.90.3.9Patch availableGHSA-j3g3-5qv5-52mj
—net-imap (RubyGems)before 0.2.50.2.5Patch availableGHSA-j3g3-5qv5-52mj
  • net-imap Vendorruby Affected 0.5.0 to before 0.5.7; 0.4.0 to before 0.4.20; 0.3.0 to before 0.3.9; before 0.2.5 Fixed in 0.5.7, 0.4.20, 0.3.9, 0.2.5 Patch available CNA
  • net-imap (RubyGems) Vendor— Affected 0.5.0 to before 0.5.7 Fixed in 0.5.7 Patch available GHSA-j3g3-5qv5-52mj
  • net-imap (RubyGems) Vendor— Affected 0.4.0 to before 0.4.20 Fixed in 0.4.20 Patch available GHSA-j3g3-5qv5-52mj
  • net-imap (RubyGems) Vendor— Affected 0.3.0 to before 0.3.9 Fixed in 0.3.9 Patch available GHSA-j3g3-5qv5-52mj
  • net-imap (RubyGems) Vendor— Affected before 0.2.5 Fixed in 0.2.5 Patch available GHSA-j3g3-5qv5-52mj

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* imapVulnerableruby
  • cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:* Versions imap Vulnerable ·ruby

Remediation

  • Fix · CNA net-imap (ruby) Fixed in 0.5.7, 0.4.20, 0.3.9, 0.2.5
  • Fix · GHSA-j3g3-5qv5-52mj net-imap (RubyGems) Fixed in 0.5.7 Advisory →
  • Fix · GHSA-j3g3-5qv5-52mj net-imap (RubyGems) Fixed in 0.4.20 Advisory →
  • Fix · GHSA-j3g3-5qv5-52mj net-imap (RubyGems) Fixed in 0.3.9 Advisory →
  • Fix · GHSA-j3g3-5qv5-52mj net-imap (RubyGems) Fixed in 0.2.5 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Logging Subsystem for Red Hat OpenShiftAffectedNo fix yet: Fix deferred
Red Hat 3scale API Management Platform 2AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 10AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 8AffectedNo fix yet: Fix deferred
Red Hat Enterprise Linux 9AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-43857
  2. 2026-10-03 Alias added: GHSA-j3g3-5qv5-52mj

References

Patch 5

Advisory 2

Other 3

  • TI-2026-30563 net-imap vulnerable to STARTTLS stripping via invalid response timing CVSS 4.0HIGH 7.6
  • TI-2026-30574 net-imap: Command Injection via unvalidated Symbol inputs CVSS 4.0MEDIUM 5.8
  • TI-2026-30572 net-imap: Denial of service via high iteration count for `SCRAM-*` authentication CVSS 4.0MEDIUM 6.0
  • TI-2026-30573 net-imap: Command Injection via "raw" arguments to multiple commands CVSS 4.0MEDIUM 5.8
  • TI-2026-30562 net-imap: Quadratic complexity when reading response literals CVSS 4.0LOW 2.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences