Resource exhaustion in Ruby Net-Imap
CVE-2025-43857
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.
Vulnerability class: DoS (Denial of Service)
EPSS: 0.005 (38.9th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H.
Affected products
- Ruby Net-imap — versions >= 0.5.0, < 0.5.7, >= 0.4.0, < 0.4.20, >= 0.3.0, < 0.3.9
- Ruby-lang Net\ — versions \
- Ruby-lang Net\:\:imap
Weakness classification (CWE)
Public proof-of-concept exploits
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
- security-advisories@github.com (Patch, x_refsource_MISC, Issue Tracking)
Frequently asked questions
- What is CVE-2025-43857?
- CVE-2025-43857 is a medium-severity vulnerability in Ruby Net-Imap, classified under Uncontrolled Resource Consumption. CVSS score: 6.5/10. Published 2025-04-28.
- How severe is CVE-2025-43857?
- Medium severity. CVSS v3 base score is 6.5 out of 10.
- Is CVE-2025-43857 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.