GHSA-2r2c-cx56-8933: JLine3 Telnet server: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry
(updated )
The JLine3 Telnet server (remote-telnet module) does not apply an upper bound to
terminal dimensions received via the Telnet NAWS (Negotiate About Window Size) option.
An unauthenticated remote attacker can send a NAWS subnegotiation advertising a
65535×65535 terminal and repeatedly alternate values to trigger continuous, expensive
rendering work on the server, causing CPU exhaustion and denial of service.
References
- github.com/advisories/GHSA-2r2c-cx56-8933
- github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708
- github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e
- github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3
- github.com/jline/jline3/pull/2000
- github.com/jline/jline3/releases/tag/4.0.16
- github.com/jline/jline3/releases/tag/4.2.1
- github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933
- nvd.nist.gov/vuln/detail/CVE-2026-56741
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