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CVE-2026-47242 — net-imap

CVE-2026-47242 is a CWE-77 vulnerability in net-imap. A fix is available for net-imap — see the affected versions and patch details below.

Net::IMAP: Command Injection via ID command argument

Also known asGHSA-46q3-7gv7-qmgg
Published
Updated
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Oct 20, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • 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 CVE-2026-47242.

EPSS Exploitation Probability

via FIRST.org ↗
0.2%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs7th percentile — riskier than 7% of all scored CVEsHighest risk
0.00%0.23%0.46%0.68%0.1%0.1%0.1%0.2%0.2%Jul 26Sep 26Oct 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

2 pkgs affected
💎net-imap💎net-imap

Real-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

Two Net::IMAP commands, #id and #enable, do not validate their arguments. Arguments to either command could be used by an attacker to inject arbitrary IMAP commands.

Please note that passing untrusted inputs to these commands is usually inappropriate and expected to be uncommon.

Details

When Net::IMAP#id is called with a hash argument, although the ID field value strings are correctly quoted (escaping quoted specials), they were not validated to prohibit CRLF sequences.

While Net::IMAP#enable does process its arguments for aliases, it does not validate them as valid atoms (or as a list of valid atoms). The #to_s value is sent verbatim.

Impact

This is expected to impact very few users: use of untrusted user input for either command is expected to be very uncommon.

The documentation for #enable explicitly warns that using any arguments that are not in the explicitly supported list may result in undocumented behavior. Using arbitrary untrusted user input for #enable will always be inappropriate.

Although client ID field values will most commonly be static and hardcoded, dynamic input sources may be used. For example, client ID fields may be set by configuration or version numbers. Using untrusted user inputs for client ID fields is expected to be uncommon. But any untrusted inputs to client ID can trivially exploit this vulnerability.

Untrusted inputs to either command may include a CRLF sequence followed by a new IMAP command (like DELETE mailbox). Although this does not directly enable data exfiltration, it could be combined with other attack vectors or knowledge of the target system's attributes, e.g.: shared mail folders or the application's installed response handlers.

Mitigation

Update to a version of net-imap which validates #id and #enable arguments.

Untrusted inputs should never be used for #enable arguments.

If net-imap cannot be upgraded:

  • do not use untrusted inputs for client ID field values
  • or add validation that client ID field values must not contain any CR or LF bytes.

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
💎RubyGemsnet-imap≥ 0.6.0&&< 0.6.4.10.6.4.1bundle update net-imap --conservative
💎RubyGemsnet-imapall versions0.5.15bundle update net-imap --conservative

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for net-imap, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update net-imap to 0.6.4.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-47242 is resolved across your whole dependency graph.

  3. Workarounds

    Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

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.

Red HatImportant

This is an Important flaw in the Net::IMAP Ruby library, which could allow a remote attacker to inject arbitrary IMAP commands. This is due to improper input validation when handling ID field values and arguments to the `enable` command. Successful exploitation requires user interaction, but could lead to manipulation…

Workaround published by Red Hat
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability. Update to the fixed version of affected product.
Source: Red Hat security advisory for CVE-2026-47242 (CC BY 4.0)
ProductFixed inAdvisory
Red Hat Enterprise Linux 10ruby4.0-0:4.0.6-36.el10_2RHSA-2026:50773
Red Hat Enterprise Linux 10ruby-0:3.3.12-14.el10_2RHSA-2026:50778
Red Hat Enterprise Linux 10.0 Extended Update Supportruby-0:3.3.12-11.el10_0.3RHSA-2026:54391
Red Hat Enterprise Linux 8ruby:3.3-8100020260727154509.489197e6RHSA-2026:50728
Red Hat Enterprise Linux 9ruby:4.0-9080020260727092509.9RHSA-2026:50827
Red Hat Enterprise Linux 9ruby:3.3-9080020260728061751.9RHSA-2026:50828
Red Hat Enterprise Linux 9.4 Update Services for SAP Solutionsruby:3.3-9040020260806064753.9RHSA-2026:54393
Red Hat Enterprise Linux 9.6 Extended Update Supportruby:3.3-9060020260805125343.9RHSA-2026:54416

Frequently Asked Questions

### Summary Two `Net::IMAP` commands, `#id` and `#enable`, do not validate their arguments. Arguments to either command could be used by an attacker to inject arbitrary IMAP commands. Please note that passing untrusted inputs to these commands is usually inappropriate and expected to be uncommon. ### Details When `Net::IMAP#id` is called with a hash argument, although the ID field value strings are correctly quoted (escaping quoted specials), they were not validated to prohibit CRLF sequences. While `Net::IMAP#enable` does process its arguments for aliases, it does not validate them as v
O3 Security · Impact-Aware SCA

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CVE-2026-47242: net-imap — Fixed in 0.6.4.1