Vulnerability details
CVE-2026-56741
jline jline3
JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry
CVSS 3.1
7.5High
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.
CVSS scores
| Score | Version | Source | Vector |
|---|---|---|---|
| 7.5High | 3.1 | CVEProject cvelistV5 (CNA) (GitHub_M) | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H |
Affected products
| Vendor | Product | Versions | Source |
|---|---|---|---|
| jline | jline3 | < 3.30.14 | CVEProject cvelistV5 (CNA) |
| jline | jline3 | >= 4.0.0, < 4.0.16 | CVEProject cvelistV5 (CNA) |
| jline | jline3 | >= 4.1.0, < 4.2.1 | CVEProject cvelistV5 (CNA) |
References and advisories
7- https://github.com/jline/jline3/pull/2000 x_refsource_MISC
- https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708 x_refsource_MISC
- https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e x_refsource_MISC
- https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3 x_refsource_MISC
- https://github.com/jline/jline3/releases/tag/4.0.16 x_refsource_MISC
- https://github.com/jline/jline3/releases/tag/4.2.1 x_refsource_MISC
- https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933 x_refsource_CONFIRM
Kolun on Telegram @kolunsec
Exploited CVEs, key news and a daily digest
Alerts for this product's next CVEsFollow the product to get new vulnerabilities on Telegram.
Details
- Published
- 2026-07-18
- Last updated
- 2026-07-20
- State
- Published
- Assigner (CNA)
- GitHub_M
Exploit prediction (EPSS)
0.59%
Probability of exploitation in 30 days
48.6%
Percentile (among all CVEs)
SSVC assessment (CISA)
- Automatable
- Yes
- Exploitation
- Proof of concept
- Technical impact
- Partial
Weaknesses (CWE)
- CWE-400Uncontrolled Resource Consumption