How severe is CVE-2026-42258?

CVE-2026-42258 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability low.

Is CVE-2026-42258 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42258?

CVE-2026-42258 affects Ruby-lang Net. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42258?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

Does CVE-2026-42258 have an EU (EUVD) identifier?

Yes. CVE-2026-42258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28927.

When was CVE-2026-42258 published?

CVE-2026-42258 was published on 2026-05-09 and last updated on 2026-07-07.

CVE-2026-42258

CVE-2026-42258 is a medium-severity vulnerability in Ruby-lang Net with a CVSS 3.x base score of 5.3. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-77.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v4: 5.8
EPSS exploit prediction: 1% (53rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28927
Weakness: CWE-77
Affected product: Ruby-lang Net
Published: 2026-05-09
Last modified: 2026-07-07

Description

Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Frequently asked questions

What is CVE-2026-42258?: Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.4.24, 0.5.14, and 0.6.4, symbol arguments to commands are vulnerable to a CRLF Injection / IMAP Command injection via Symbol arguments passed to IMAP commands. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
How severe is CVE-2026-42258?: CVE-2026-42258 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over local access with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is none, integrity high, and availability low.
Is CVE-2026-42258 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (53rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42258?: CVE-2026-42258 affects Ruby-lang Net. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42258?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
Does CVE-2026-42258 have an EU (EUVD) identifier?: Yes. CVE-2026-42258 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28927.
When was CVE-2026-42258 published?: CVE-2026-42258 was published on 2026-05-09 and last updated on 2026-07-07.

References

Affected products (1)

cpe:2.3:a:ruby-lang:net\:\:imap:*:*:*:*:*:ruby:*:*

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