ALAS2027-2026-231

References: CVE-2026-77423  CVE-2026-77420  CVE-2026-77421 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Package updates are available for Amazon Linux 2027 that fix the following vulnerabilities:
CVE-2026-77423:
JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, the JLine built-in less viewer passes user-controlled search and display-filter patterns from getPattern(boolean doDisplayPattern) in builtins/src/main/java/org/jline/builtins/Less.java directly to Java's backtracking regular expression engine and repeatedly applies them to file content. A nested-quantifier expression evaluated against non-matching lines can consume excessive CPU and indefinitely block the session thread, and repeated sessions in Telnet or SSH deployments can exhaust a bounded worker pool. This issue is fixed in versions 3.30.15 and 4.3.1.

CVE-2026-77421:
JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, the JLine built-in nano editor's regex search mode passes a user-controlled search term from doSearch(String text) in builtins/src/main/java/org/jline/builtins/Nano.java to Java's backtracking regular expression engine without a timeout or backtracking bound. A nested-quantifier expression evaluated against non-matching buffer content can consume excessive CPU and indefinitely block the editor session thread, and remote multi-user deployments can lose a worker thread for each affected session. This issue is fixed in versions 3.30.15 and 4.3.1.

CVE-2026-77420:
JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, DefaultHistory.matchPatterns(String patterns, String line) in reader/src/main/java/org/jline/reader/impl/history/DefaultHistory.java converts the HISTORY_IGNORE configuration value into a Java regular expression while escaping only part of its syntax, allowing other regex metacharacters to reach the backtracking engine. An attacker who can control application or user configuration can supply a nested-quantifier expression that is reevaluated whenever a command is added to history, consuming excessive CPU and indefinitely blocking the reader thread. This issue is fixed in versions 3.30.15 and 4.3.1.

Issue Correction:
Run dnf update jline or dnf update --advisory ALAS2027-2026-231 to update your system.

New Packages:

aarch64:
    jline-debuginfo-3.30.15-1.amzn2027.0.1.aarch64
    jline-debugsource-3.30.15-1.amzn2027.0.1.aarch64
    jline-3.30.15-1.amzn2027.0.1.aarch64

src:
    jline-3.30.15-1.amzn2027.0.1.src

x86_64:
    jline-debugsource-3.30.15-1.amzn2027.0.1.x86_64
    jline-debuginfo-3.30.15-1.amzn2027.0.1.x86_64
    jline-3.30.15-1.amzn2027.0.1.x86_64