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CVE-2026-56740 JLine

Affected softwareJLine
Severity7.5 High CVSS 3.1
Fixed in4.2.1, 4.0.16, 3.30.14
WeaknessUncontrolled resource consumption (CWE-400)
Published17 Jul 2026
Updated24 Oct 2026

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 limit the number of environment variables a client may inject via the Telnet NEW-ENVIRON option, and TelnetIO.readNEVariables() in TelnetIO.java:1127-1180 stores each variable pair in a HashMap held by ConnectionData, allowing an unauthenticated attacker to flood unique variable pairs before the terminating IAC SE byte and exhaust JVM heap memory with an OutOfMemoryError. This issue is fixed in versions 3.30.14, 4.0.16, and 4.2.1.

Exploitation status

Proof of concept only

A proof of concept exists, but no reviewed exploit catalogue lists this CVE.

  • CISA KEV not listed
  • VulnCheck KEV not listed
  • CISA Vulnrichment exploitation: poc CISA recorded that an exploit has been demonstrated. Automatable: yes, technical impact: partial.
  • Indexed PoC none indexed
  • EPSS 0.59% chance in 30 days

Waratek protection

No exploit published

Within Waratek scope. In the sources we check, nobody has published exploit code for this CVE or reported it being exploited.

A public code fix exists: jline/jline3 0389f0e.

  • Protection none
  • Action unverified
  • Review automated Upstream data
  • Record active
Decided by Exploit code for this candidate, published in a reviewed catalogue or a GitHub repository with 5 or more stars, or in use per CISA or VulnCheck; not only a CISA verdict, a forecast, or nothing at all
Finding This CVE is not listed in CISA KEV or VulnCheck KEV, CISA Vulnrichment records no active exploitation, no reviewed exploit catalogue carries an entry for it, and no GitHub PoC repository for it has 5 or more stars. Nobody has published exploit code worth tracing, so it is not a candidate for a rule ahead of the ones where somebody has; an upstream fix path does exist, so the remediation half of the candidacy still holds. This is a statement about what has been published, not about whether the defect is reachable or serious.
Candidate fix https://github.com/jline/jline3/commit/0389f0ee6d0375901b602671ad5dafd4d1d4ee09 : a commit: the change itself

Affected software and releases

Oracle advisories

AdvisoryTypeQuarterProducts Oracle names in its risk matrix
Oracle Critical Patch Update October 2026 ↗ CPU 2026-Q4 Oracle Communications / BRM Server (jline) (15.0.0.0.0, 15.0.1.0.0, 15.1.0.0.0, 15.2.0.0.0)

Oracle components and versions

FamilyComponentVersions, as Oracle lists themRead as
Oracle Communications BRM Server (jline) 15.0.0.0.0, 15.0.1.0.0, 15.1.0.0.0, 15.2.0.0.0 15.0.0.0.0 · 15.0.1.0.0 · 15.1.0.0.0 · 15.2.0.0.0

Maven packages

Affected and fixed versions, from OSV.dev
PackageIntroducedFixedLast affected
org.jline:jline-remote-telnet 4.1.0 4.2.1 unbounded
org.jline:jline-remote-telnet 4.0.0 4.0.16 unbounded
org.jline:jline-remote-telnet 0 3.30.14 unbounded

Products and versions

2 products, 6 version entries
SourceVendorProductSchemeAffected versions
nvd jline jline generic < 3.30.14 · ≥ 4.0.0 and < 4.0.16 · ≥ 4.1.0 and < 4.2.1
osv org.jline jline-remote-telnet generic < 3.30.14 · ≥ 4.0.0 and < 4.0.16 · ≥ 4.1.0 and < 4.2.1

References

URLTags
https://github.com/jline/jline3/commit/0389f0ee6d0375901b602671ad5dafd4d1d4ee09 commit
https://github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f WEB
https://github.com/jline/jline3/pull/2000 WEB
https://github.com/jline/jline3/pull/2001 WEB
https://github.com/jline/jline3/commit/4ee3a73849ffb9a85ec748e4e8cd8f6d81f84f40 WEB
https://github.com/jline/jline3/commit/934f09e6128cee33c2b13d42b6e859c1ee2d194b WEB
https://github.com/jline/jline3 PACKAGE
https://github.com/jline/jline3/releases/tag/4.0.16 WEB
https://github.com/jline/jline3/releases/tag/4.2.1 WEB
https://github.com/jline/jline3/releases/tag/jline-3.30.14 WEB

Timeline

Published2026-07-17By the CVE Program.
NVD record modified2026-10-24NVD's own last-modified date for this record.