GHSA-vcgp-9326-pqcp
Fix: ruby/net-imap@0ede4c4GHSA-vcgp-9326-pqcp is a CWE-392 vulnerability in net-imap. O3 Security confirms whether GHSA-vcgp-9326-pqcp is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
net-imap vulnerable to STARTTLS stripping via invalid response timing
Exploitation Status
No confirmed exploitation observed yet
- A successful exploit gives an attacker total control of the affected component, not partial access.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-vcgp-9326-pqcp.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
Real-World Exposure
net-imap💎net-imap💎net-imap💎net-imapReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects RubyGems packages — download data is not available via public APIs for these ecosystems.
Description
Summary
A man-in-the-middle attacker can cause Net::IMAP#starttls to return "successfully", without starting TLS.
Details
When using Net::IMAP#starttls to upgrade a plaintext connection to use TLS, a man-in-the-middle attacker can inject a tagged OK response with an easily predictable tag. By sending the response before the client finishes sending the command, the command completes "successfully" before the response handler is registered. This allows #starttls to return without error, but the response handler is never invoked, the TLS connection is never established, and the socket remains unencrypted.
This allows man-in-the-middle attackers to perform a STARTTLS stripping attack, unless the client code explicitly checks Net::IMAP#tls_verified?.
Impact
TLS bypass, leading to cleartext transmission of sensitive information.
Mitigation
- Upgrade to a patched version of net-imap that raises an exception whenever
#starttlsdoes not establish TLS. - Connect to an implicit TLS port, rather than use
STARTTLSwith a cleartext port. This is strongly recommended anyway:- RFC 8314: Cleartext Considered Obsolete: Use of Transport Layer Security (TLS) for Email Submission and Access
- NO STARTTLS: Why TLS is better without STARTTLS, A Security Analysis of STARTTLS in the Email Context
- Explicitly verify
Net::IMAP#tls_verified?istrue, before using the connection after#starttls.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 💎RubyGems | net-imap | ≥ 0.6.0&&< 0.6.4 | 0.6.4 |
| 💎RubyGems | net-imap | ≥ 0.5.0&&< 0.5.14 | 0.5.14 |
| 💎RubyGems | net-imap | ≥ 0.4.0&&< 0.4.24 | 0.4.24 |
| 💎RubyGems | net-imap | all versions | 0.3.10 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net-imap. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update net-imap to 0.6.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-vcgp-9326-pqcp is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-vcgp-9326-pqcp is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to GHSA-vcgp-9326-pqcp. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability affects the STARTTLS functionality in the Ruby net-imap library. Red Hat Product Security has assessed this issue as an Important severity vulnerability. Attack Complexity is considered High (AC:H), because successful exploitation requires an attacker capable of intercepting and modifying network…
Frequently Asked Questions
Is GHSA-vcgp-9326-pqcp in your dependencies?
O3 detects GHSA-vcgp-9326-pqcp across RubyGems dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.