How severe is CVE-2026-42245?

CVE-2026-42245 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-42245 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42245?

CVE-2026-42245 affects Ruby-lang Net. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-42245?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42245 have an EU (EUVD) identifier?

Yes. CVE-2026-42245 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28923.

When was CVE-2026-42245 published?

CVE-2026-42245 was published on 2026-05-09 and last updated on 2026-06-17.

CVE-2026-42245

CVE-2026-42245 is a high-severity vulnerability in Ruby-lang Net with a CVSS 3.x base score of 7.5. 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-407.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 2.3
EPSS exploit prediction: 0% (33rd percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-28923
Weakness: CWE-407
Affected product: Ruby-lang Net
Published: 2026-05-09
Last modified: 2026-06-17

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, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.

Frequently asked questions

What is CVE-2026-42245?: 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, Net::IMAP::ResponseReader has quadratic time complexity when reading large responses containing many string literals. A hostile server can send responses which are crafted to exhaust the client's CPU for a denial of service attack. This issue has been patched in versions 0.4.24, 0.5.14, and 0.6.4.
How severe is CVE-2026-42245?: CVE-2026-42245 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-42245 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (33rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42245?: CVE-2026-42245 affects Ruby-lang Net. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-42245?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42245 have an EU (EUVD) identifier?: Yes. CVE-2026-42245 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-28923.
When was CVE-2026-42245 published?: CVE-2026-42245 was published on 2026-05-09 and last updated on 2026-06-17.

References

Affected products (1)

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

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