CVE-2026-56741

HIGHPre-NVD 7.57.5—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.5%, top 59% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Trending — 3 sources updated this weekElevated
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0

No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.

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 v3
7.5
EG Score
7.5(medium)
EG Risk
65(Attend)
EG Risk 65/100SSVC: Attend

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity75% × 45%
Exploitation40% × 40%
Automatability100% × 15%
Action: Remediate soon — notable exploitation risk.
EPSS
41.1%
KEV
Not listed

Published

July 17, 2026

Last Modified

July 23, 2026

Advisory Details (7)

Auto-updated Jul 17, 2026
🔬 Proof of concept available. Patch available. Sources: github, github_pr, github_commit, github_release.
github_release Patch Available

JLine 4.2.1

Patch available: jline/jline3 4.2.1

https://github.com/jline/jline3/releases/tag/4.2.1
github_release Patch Available

JLine 4.0.16

Patch available: jline/jline3 4.0.16

https://github.com/jline/jline3/releases/tag/4.0.16
github_commit Patch Available

commit 86b7ba780198 (jline/jline3)

Patch available: jline/jline3 4.0.16 (contains commit 86b7ba780198)

https://github.com/jline/jline3/commit/86b7ba7801988aadb1a67555629522a71d603bd3
github_commit Patch Available

commit 733eb353dca7 (jline/jline3)

Patch available: jline/jline3 4.2.1 (contains commit 733eb353dca7)

https://github.com/jline/jline3/commit/733eb353dca7b0ea0252e724445b6defa29c393e
github_commit Patch Available

commit 3ea9cad86997 (jline/jline3)

Patch available: jline/jline3 jline-3.30.14 (contains commit 3ea9cad86997)

https://github.com/jline/jline3/commit/3ea9cad8699714dc072fade29d36be0d1e23d708
github_pr Patch Available

fix: backport telnet DoS mitigations (GHSA-47qp, GHSA-2r2c) to 3.x

Patch available: jline/jline3 jline-3.30.14 (PR #2000 merged 2026-06-26)

https://github.com/jline/jline3/pull/2000
github Patch Available🟡 PoC Available

Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry · Advisory · jline/jline3 · GitHub

https://github.com/jline/jline3/security/advisories/GHSA-2r2c-cx56-8933

Vendor Advisories for CVE-2026-56741(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(1 across 1 ecosystem)
Maven(1)
PackageVulnerable rangeFixed inDependents
org.jline:jline-remote-telnet3.10.0 ... 4.2.0 (85 versions)4.2.1—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 12× in last 7d / 12× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

  1. 2026-07-23 14:18 UTCEPSS rescore
  2. 2026-07-23 03:20 UTCEG score recompute
  3. 2026-07-22 14:08 UTCEPSS rescore
  4. 2026-07-21 15:25 UTCEPSS rescore
  5. 2026-07-20 17:56 UTCEG score recompute
  6. 2026-07-20 17:08 UTCEPSS rescore
  7. 2026-07-19 14:31 UTCEPSS rescore
  8. 2026-07-19 14:31 UTCEPSS rescore
  9. 2026-07-19 02:29 UTCEPSS rescore
  10. 2026-07-18 00:03 UTCEG score recompute
  11. 2026-07-17 21:19 UTCEG score recompute
  12. 2026-07-17 21:19 UTCMITRE cvelistV5first tracked

Related CVEs(same CWE)

Frequently asked(5)

What is CVE-2026-56741?
CVE-2026-56741 is a high vulnerability published on July 17, 2026. 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…
When was CVE-2026-56741 disclosed?
CVE-2026-56741 was first published in the National Vulnerability Database on July 17, 2026, with the most recent update on July 23, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-56741 actively exploited?
CVE-2026-56741 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 41.1% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-56741?
CVE-2026-56741 has a CVSS v3 base score of 7.5 (NVD).
How do I remediate CVE-2026-56741?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-56741, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-56741

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