Vulnerability in jline3

[ Why it matters ]Priority signals

• Public proof-of-concept exploit exists (CISA SSVC)

[ Description ]Official description

JLine is a Java library for handling console input. Prior to 3.30.14, 4.0.16, and 4.2.1, the JLine3 Telnet server remote-telnet module does not apply an upper bound to terminal dimensions received via the Telnet NAWS option, and TelnetIO.handleNAWS() in TelnetIO.java:856-879 reads client-supplied width and height as 16-bit unsigned integers and passes values such as 65535x65535 to setTerminalGeometry(), allowing an unauthenticated remote attacker to repeatedly alternate values and trigger continuous expensive rendering work that causes CPU exhaustion and denial of service. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1.

[ Fixes ]Fixes and patches

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ Advisories ]Government CERT advisories

• NCSC-NL22 Oct 2026NCSC-2026-0448

  Vulnerabilities fixed in Oracle Fusion Middleware Translated from Dutch

  Probability/damage H/HCVE-2026-54513CVE-2026-56741CVE-2026-59649+191 more CVEs
• BSI CERT-Bund20 Oct 2026WID-SEC-2026-4078

  Oracle Fusion Middleware: Multiple vulnerabilities Translated from German

  CVE-2026-91212CVE-2023-43622CVE-2026-42779+191 more CVEs

[ References ]References

• github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933x_refsource_CONFIRM
• github.com/jline/jline3/pull/2000x_refsource_MISC
• github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708x_refsource_MISC
• github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393ex_refsource_MISC
• github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3x_refsource_MISC
• github.com/jline/jline3/releases/tag/4.0.16x_refsource_MISC
• github.com/jline/jline3/releases/tag/4.2.1x_refsource_MISC