Red Hat Security Advisory: ruby4.0 security, bug fix, and enhancement update

Fixed packages 9

Vulnerabilities 6

• Medium 6.0
  CVE-2026-42256

  net-imap: Denial of service via high iteration count for `SCRAM-*` authentication

  Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. From versions 0.4.0 to before 0.4.24, 0.5.0 to before 0.5.14, and 0.6.0 to before 0.6.4, when authenticating a connection with SCRAM-SHA1 or SCRAM-SHA256, a hostile ser…

  ruby net-imap logstash-9.3 logstash-9.3-iamguarded-compat Debian Ubuntu Alpine Wolfi RubyGems
  May 9, 2026
• Medium 5.8
  CVE-2026-42257

  net-imap: Command Injection via "raw" arguments to multiple commands

  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, several Net::IMAP commands accept a raw string argument that is sent to the server without validation or escaping. If this …

  ruby net-imap logstash-9.3 logstash-9.3-iamguarded-compat Debian Ubuntu Alpine Wolfi RubyGems
  May 9, 2026
• Medium 5.8
  CVE-2026-47240

  Net::IMAP: Command Injection via non-synchronizing literal in "raw" argument

  Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a "raw data" argument that is sent verbatim after validation to prevent command injection. However, if a se…

  ruby net-imap logstash-9.3-iamguarded-compat logstash-9.3 Debian Ubuntu Azure Linux Alpine Wolfi RubyGems
  Jun 22, 2026
• Medium 5.8
  CVE-2026-47242

  Net::IMAP: Command Injection via ID command argument

  Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, when Net::IMAP#id is called with a hash argument, although the ID field value strings are correctly quoted (escaping quoted specials), they w…

  ruby net-imap logstash-9.3-iamguarded-compat logstash-9.3 Debian Ubuntu Azure Linux Alpine Wolfi RubyGems
  Jun 22, 2026
• Low 2.1
  CVE-2026-47241

  Net::IMAP: Denial of Service via incomplete raw argument validation

  Net::IMAP implements Internet Message Access Protocol (IMAP) client functionality in Ruby. Prior to 0.6.5 and 0.5.15, several Net::IMAP commands accept a raw string argument which is only validated to prevent CRLF injection and then sent verbatim. If this str…

  ruby net-imap logstash-9.3-iamguarded-compat logstash-9.3 Debian Ubuntu Alpine Wolfi RubyGems
  Jun 22, 2026
• Low 1.7
  CVE-2026-27820

  zlib: Buffer Overflow in Zlib::GzipReader ungetc via large input leads to memory corruption

  zlib is a Ruby interface for the zlib compression/decompression library. Versions 3.0.0 and below, 3.1.0, 3.1.1, 3.2.0 and 3.2.1 contain a buffer overflow vulnerability in the Zlib::GzipReader. The zstream_buffer_ungets function prepends caller-provided bytes…

  ruby zlib ruby2.3 ruby Debian Ubuntu Azure Linux Alpine RubyGems
  Apr 16, 2026

References

• article
  https://access.redhat.com/security/updates/classification/#important
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2459002
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2468494
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2468500
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2491519
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2491522
• report
  https://bugzilla.redhat.com/show_bug.cgi?id=2491523
• advisory
  https://security.access.redhat.com/data/csaf/v2/advisories/2026/rhsa-2026_50773.json
• report
  https://access.redhat.com/security/cve/CVE-2026-27820
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-27820
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-27820
• article
  https://github.com/ruby/zlib/security/advisories/GHSA-g857-hhfv-j68w
• article
  https://hackerone.com/reports/3467067
• report
  https://access.redhat.com/security/cve/CVE-2026-42256
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-42256
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-42256
• article
  https://github.com/ruby/net-imap/commit/158d0b505074397cdb5ceb58935e42dd2bcfa612
• article
  https://github.com/ruby/net-imap/commit/808001bc45c06f7297a7e96d341279e041a7f7f4
• article
  https://github.com/ruby/net-imap/commit/99f59eab6064955a23debd95410263ad144df758
• article
  https://github.com/ruby/net-imap/releases/tag/v0.4.24
• article
  https://github.com/ruby/net-imap/releases/tag/v0.5.14
• article
  https://github.com/ruby/net-imap/releases/tag/v0.6.4
• article
  https://github.com/ruby/net-imap/security/advisories/GHSA-87pf-fpwv-p7m7
• report
  https://access.redhat.com/security/cve/CVE-2026-42257
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-42257
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-42257
• article
  https://github.com/ruby/net-imap/security/advisories/GHSA-hm49-wcqc-g2xg
• report
  https://access.redhat.com/security/cve/CVE-2026-47240
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-47240
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-47240
• article
  https://github.com/ruby/net-imap/security/advisories/GHSA-8p34-64r3-mwg8
• report
  https://access.redhat.com/security/cve/CVE-2026-47241
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-47241
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-47241
• article
  https://github.com/ruby/net-imap/security/advisories/GHSA-c4fp-cxrr-mj66
• report
  https://access.redhat.com/security/cve/CVE-2026-47242
• advisory
  https://www.cve.org/CVERecord?id=CVE-2026-47242
• advisory
  https://nvd.nist.gov/vuln/detail/CVE-2026-47242
• article
  https://github.com/ruby/net-imap/security/advisories/GHSA-46q3-7gv7-qmgg