CVE-2026-42246: ruby net-imap · Missing Report of Error Condition
Affects ruby net-imapSource CVE Database V5
Not known to be exploited · CVSS 7.6 High · fixed in 0.6.4 : patch ruby net-imap soon.
Data as of 10 Nov 2026, 23:24 UTC
- EPSS
- 0.3% chance of exploitation in 30 days – higher than 24% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 0.6.4, 0.5.14, 0.4.24 +1
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:N/SI:N/SA:NExploitation evidence
Disclosed: evidence found.
CVE published 9 May 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.
What to do
Upgrade ruby net-imap to 0.6.4, 0.5.14, 0.4.24 or 0.3.10.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| rubynet-imap | Affected
| Fixed in
|
| rubynet-imap | Affected
| Fixed in
|
| rubynet-imap | Affected
| Fixed in
|
| rubynet-imap | Affected
| Fixed in
|
AI-suggested
A fix is available in net-imap versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4 and later. Users should upgrade to these patched versions to remediate the vulnerability. As a temporary workaround, it is strongly recommended to avoid using STARTTLS on port 143 and instead use implicit TLS connections (IMAPS) on port 993, which are not vulnerable to this attack vector. Red Hat has released security updates for affected Ruby packages in Red Hat Enterprise Linux 7 Extended Lifecycle Support. Users should apply these updates promptly.
Description
Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4, a man-in-the-middle attacker can cause Net::IMAP#starttls to return "successfully", without starting TLS. This issue has been patched in versions 0.3.10, 0.4.24, 0.5.14, and 0.6.4.
References
- github.com/ruby/net-imap/security/advisories/GHSA-vcgp-9326-pqcp (opens in a new tab)
- github.com/ruby/net-imap/commit/0ede4c40b1523dfeaf95777b2678e54cc0fd9618 (opens in a new tab)
- github.com/ruby/net-imap/commit/24a4e770b43230286a05aa2a9746cdbb3eb8485e (opens in a new tab)
- github.com/ruby/net-imap/commit/97e2488fb5401a1783bddd959dde007d9fbce42c (opens in a new tab)
- github.com/ruby/net-imap/commit/f79d35bf5833f186e81044c57c843eda30c873da (opens in a new tab)
- github.com/ruby/net-imap/releases/tag/v0.3.10 (opens in a new tab)
- github.com/ruby/net-imap/releases/tag/v0.4.24 (opens in a new tab)
- github.com/ruby/net-imap/releases/tag/v0.5.14 (opens in a new tab)
- access.redhat.com/security/cve/CVE-2026-42246 (opens in a new tab)
- bugzilla.redhat.com/show_bug.cgi?id=2468499 (opens in a new tab)
- security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-42246.json (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:37397 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35895 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33565 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33540 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33514 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33515 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35866 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35867 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:34076 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:35834 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33630 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:36099 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33462 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:37238 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33512 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33576 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33577 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33721 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33552 (opens in a new tab)
- access.redhat.com/errata/RHSA-2026:33551 (opens in a new tab)