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Fencer Intel
high 7.5

CVE-2026-56740 json

JLine: Unauthenticated Remote Memory Exhaustion via Unbounded Telnet NEW-ENVIRON Variables

published 4mo ago modified 18d ago also EUVD-2026-45343 , GHSA-47qp-hqvx-6r3f

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.6%
EPSS 0.6% chance of exploitation in 30 days, percentile 48%
public exploits
0
none known

Summary

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.

Patch / fix

  • maven org.jline:jline-remote-telnet 3.30.14, 4.0.16, 4.2.1
  • jline jline 3.30.14, 4.0.16, 4.2.1
  • org.jline jline-remote-telnet 3.30.14, 4.0.16, 4.2.1
  • jline3 Debian 14 3.29.0+ds-2

debian advisories DEBIAN-CVE-2026-56740

  • jline3 SLES for SAP applications 16.0, SLES 16.0 3.30.15-160000.1.1

suse advisories SUSE-SU-2026:22856-1

  • jline3 openSUSE Leap 16.0 3.30.15-160000.1.1
  • jline3 openSUSE Tumbleweed 3.30.15-3.1

opensuse advisories openSUSE-SU-2026:21423-1openSUSE-SU-2026:11338-1

Is CVE-2026-56740 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-56740 updated cvss 7.5

org.jline/jline-remote-telnet: JLine3 Telnet Server: Denial of Service via excessive environment variable injection

  • Red Hat Fuse 7 jline-remote-telnet
    not affected: vulnerable code not present
  • Red Hat OpenShift AI (RHOAI) rhoai/odh-spark-operator-rhel9, rhoai/odh-th-torch-cpu-py312-rhel9, rhoai/odh-th-torch-cuda-py312-rhel9, rhoai/odh-th06-cpu-torch210-py312-rhel9, rhoai/odh-th06-cpu-torch291-py312-rhel9, rhoai/odh-th06-rocm64-torch291-py312-rhel9, +2 more
    not affected: vulnerable code not in execute path

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.59% chance of exploitation in the next 30 days, higher than 48% of all scored CVEs (FIRST EPSS, 2026-11-11).

Exploits and checks

  • github.com https://github.com/jline/jline3/security/advisories/GHSA-47qp-hqvx-6r3f referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
GitHub 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected packages

ecosystem package affected fixed in
maven org.jline:jline-remote-telnet
>=4.1.0, <4.2.1
>=4.0.0, <4.0.16
<3.30.14
4.2.1
4.0.16
3.30.14

Affected products

  • jline jline3

Classification

Weakness
  • CWE-400 Uncontrolled Resource Consumption

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.