7.5

CVE-2026-56741: JLine: Unauthenticated Remote DoS via Unbounded Telnet NAWS Terminal Geometry

Analyzed
AliasesUBUNTU-CVE-2026-56741DEBIAN-CVE-2026-56741CGA-35qw-9mx9-9j7h
Published 17-07-2026Last modified 20-07-2026

Vulnerability summary

CVE-2026-56741 is a high (CVSS 7.5) Uncontrolled Resource Consumption vulnerability in jline. EPSS estimates a 0.60% chance of exploitation in the next 30 days, higher than 48.5% of scored vulnerabilities. 1 public exploit is recorded.

Priority
Prioritisepublic exploit

Public exploit (GitHub, Date unknown)

Source freshness unavailable

How is this decided?
CVSS score
7.5/10
010
High · v3.1 (CVE.org)
EPSS score
0.60%
0%100%
Low · -0.29 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits1github

Advisory lineage

Upstream 0 · Downstream 3 · Related 4
OPENSUSE-SU-2026:11338-1OPENSUSE-SU-2026:21423-1SUSE-SU-2026:22856-1CGA-FJ2H-M2VP-F2J5

Timeline

  1. 17-07-2026
    PublishedVulnerability first disclosed.
  2. 20-07-2026
    Last modifiedVulnerability information updated.

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 metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.60%

Chance of exploitation in the next 30 days

Percentile

49%

Versus all other CVEs

30-day change

Decrease -0.29 pp

From 0.89% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

1 found
  • githubUnverified

    Jline3

    Maturity: poc

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, no authentication, no user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard58 products
  • apache-camel-karavan-devmode< 4.18.1-r5
  • apache-hop< 2.18.1-r1
  • apache-hop-fips< 2.18.1-r1
  • apache-nifi-toolkit< 2.10.0-r1
  • apache-polarisAll versions (No fix recorded)
Wolfi13 products
  • apache-nifi-toolkit< 2.10.0-r1
  • apache-pulsar-4.1All versions (No fix recorded)
  • apache-pulsar-4.2< 4.2.2-r4
  • celeborn-0.6All versions (No fix recorded)
  • confluent-kafka< 8.4.0.269-r1
Debian3 products
  • jlineAll versions (No fix recorded)
  • jline2All versions (No fix recorded)
  • jline3All versions (No fix recorded)
Ubuntu3 products
  • jlineAll versions (No fix recorded)
  • jline2All versions (No fix recorded)
  • jline3All versions (No fix recorded)
Jline2 products
  • jline< 3.30.14 | ≥ 4.0.0, < 4.0.16 | ≥ 4.1.0, < 4.2.1
  • jline3< 3.30.14 | ≥ 4.0.0, < 4.0.16 | ≥ 4.1.0, < 4.2.1
Org.jline1 product
  • jline-remote-telnet≥ 4.1.0, < 4.2.1 | ≥ 4.0.0, < 4.0.16 | < 3.30.14

6 vendors · 80 products

References

13 links
Show all 13 references