JLine: ReDoS in Built-in grep Command Amplified by Automatic .* Wrapping

Exploitation

No confirmed exploitation recorded. Patch Next marks exploitation only from CISA KEV.

CVSS

7.5 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

• CVE-2026-77422: 0.60% estimated exploitation activity in the next 30 days; percentile 48.47 (FIRST EPSS, 2026-11-03). This is a model estimate, not proof of exploitation or customer exposure.

As published by the source; long descriptions are shortened.

Summary The JLine3 built-in grep command wraps the user-supplied regular expression with . before compiling it with Java's backtracking regex engine. This amplifies catastrophic backtracking and allows a short pattern such as (a+)+b to hang the command thread on non-matching input. In environments that expose the JLine shell to remote users, this is a denial-of-service issue. Details In builtins/src/main/java/org/jline/builtins/PosixCommands.java, the grep implementation rewrites the user pattern before compilation: The transformed pattern is compiled with Pattern.compile(...) and then used to test each input line. For a payload such as (a+)+b, the automatic . prefix and suffix increase the backtracking search space substantially. Affected source location: - builtins/src/main/java/org/jline/builtins/PosixCommands.java - grep(...) PoC 1. Create a file containing a long run of a characters: 2. Run JLine3's built-in grep against that file: Expected result: - The command stops…

Published by the source

23 Sep 2026, 18:12 UTC

Last modified by the source

23 Sep 2026, 18:27 UTC

Source last checked

26 Oct 2026, 16:55 UTC

1. Revision 2 · amended · 26 Oct 2026

   Amended from ghsa record GHSA-r2xf-8xr9-62gw

2. Revision 1 · created · 24 Oct 2026

   Published from osv record GHSA-r2xf-8xr9-62gw

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# Patch Next advisory brief: CVE-2026-77422

Advisory: JLine: ReDoS in Built-in grep Command Amplified by Automatic `.*` Wrapping
IDs: CVE-2026-77422, GHSA-r2xf-8xr9-62gw
Record: https://patchnext.com/advisories/cve-2026-77422 (revision 2, source checked 26 Oct 2026, 16:55 UTC)
Inventory: none attached. This brief comes from a public page and does not say whether any deployment is affected.
Severity: High (CVSS 7.5)
Exploitation: no confirmed exploitation recorded. Patch Next confirms exploitation only from CISA KEV.
Vendor response: Vendor fix available; fixed versions by package: org.jline:jline-builtins 4.3.1, 3.30.15. A vendor fix does not mean a deployment is fixed.

## Affected components
- Maven org.jline:jline-builtins: affected >= 4.0.0, < 4.3.1; >= 3.0.0, < 3.30.15; fixed in 4.3.1, 3.30.15

## Suggested inspection (read-only)
- Maven org.jline:jline-builtins: check the installed version with your package manager.

## Supported action
Upgrade each affected component to a fixed version on its release line. For a transitive dependency, upgrade the parent package or add an override or constraint, then regenerate the lockfile. Redeploy every environment that ran an affected version.

## Required regression checks
- Run the test suite and a production build.
- Exercise the features that depend on org.jline:jline-builtins.
- Repeat the inspection and confirm that only fixed versions remain installed.

## Rollback considerations
- Keep the previous lockfile and deployment artifact. Rolling back reinstates the vulnerable version, so apply any documented mitigation while you fix forward.

## Unresolved questions
- Which deployments run an affected version?
- Exploitation status can change. Check again before lowering the priority.
- Mark the work resolved only after the fixed version is verified in production.

## Sources
- Verified: https://osv.dev/vulnerability/GHSA-r2xf-8xr9-62gw (OSV record GHSA-r2xf-8xr9-62gw lists affected ranges: Maven org.jline:jline-builtins >=4.0.0 =3.0.0 <3.30.15 (fixed))
- Verified: https://github.com/advisories/GHSA-r2xf-8xr9-62gw (GitHub-reviewed advisory GHSA-r2xf-8xr9-62gw lists affected ranges: Maven org.jline:jline-builtins >=4.0.0 =3.0.0 <3.30.15)

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