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VulnerabilityPublished Updated

CVE-2026-77420: jline jline3 · ReDoS

Affects jline jline3Source CVE Database V5

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Not known to be exploited · CVSS 5.5 Medium : upgrade to 4.3.1 or 3.30.15 when convenient.

Data as of 7 Nov 2026, 23:24 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 4.3.1, 3.30.15
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 23 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 7 Nov 2026.

What to do

Upgrade jline3 and org.jline/jline3 to 4.3.1 or 3.30.15.

Affected software

ProductAffectedFixed in
jlinejline3Affected
  • >=4.0.0 <4.3.1
Fixed in
  • 4.3.1
jlinejline3Affected
  • >=3.0.0 <3.30.15
Fixed in
  • 3.30.15
Mavenorg.jline/jline3pkg:maven/org.jline/jline3Other threatsAffected
  • >=3.0.0 <3.30.15
  • >=4.0.0 <4.3.1
Fixed in
  • 3.30.15
  • 4.3.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

This vulnerability is fixed in jline3 versions 3.30.15 and 4.3.1. Users should upgrade to these or later versions to remediate the issue. No other mitigations are indicated by the vendor advisory.

Description

CVE-2026-77420 is a medium severity vulnerability in the jline3 Java library affecting versions from 3.0.0 up to but not including 3.30.15 and from 4.0.0 up to but not including 4.3.1. The flaw arises from inefficient regular expression handling in the DefaultHistory.matchPatterns method, where partial escaping of regex syntax allows nested quantifiers to cause excessive CPU consumption and indefinite blocking of the reader thread. This can be triggered by an attacker controlling application or user configuration. The issue is fixed in versions 3.30.15 and 4.3.1.

References

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