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Critical Ruby Vulnerabilities in IMAP and GzipReader Affecting Ubuntu

Critical Ruby Vulnerabilities in IMAP and GzipReader Affecting Ubuntu

First seen 17 Jul 2026, 08:27 UTC

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ThreatCluster AI
ThreatCluster July 18, 2026 at 07:39 UTC
  • CVE-2026-42258 allows remote command injection in the Net::IMAP client.
  • CVE-2026-27820 can cause buffer overflow and memory corruption in Zlib::GzipReader.
  • Affected systems include Ruby 2.3 on Ubuntu; updates are available via standard system updates.

Two critical vulnerabilities were discovered in Ruby affecting the Net::IMAP client and Zlib::GzipReader. CVE-2026-42258 allows remote attackers to inject arbitrary IMAP commands via CRLF sequences, while CVE-2026-27820 can lead to a buffer overflow through crafted gzip streams. These vulnerabilities impact Ruby 2.3 and could lead to memory corruption or arbitrary code execution. The issues were published on May 9, 2026, and April 16, 2026, respectively. Affected users are advised to update their systems to mitigate these risks. Ubuntu Pro users can receive extended security coverage for these packages. A standard system update will address these vulnerabilities.

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Timeline

2026-04-16
CVE-2026-27820 published
A buffer overflow vulnerability in Zlib::GzipReader was disclosed, allowing potential memory corruption.
Ubuntu
2026-05-09
CVE-2026-42258 published
A critical vulnerability in the Net::IMAP client was disclosed, enabling command injection via CRLF sequences.
Ubuntu
2026-07-16
Security updates released
Ubuntu released updates to address the critical vulnerabilities in Ruby, urging users to apply them immediately.
Linuxsecurity

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