Vulnerability-Lookup

GHSA-R2XF-8XR9-62GW

Vulnerability from github – Published: 2026-09-23 18:12 – Updated: 2026-09-23 18:12

Summary

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

Details

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:

String regex = args.remove(0);
String regexp = regex;
if (opt.isSet("word-regexp")) {
    regexp = "\\b" + regexp + "\\b";
}
if (opt.isSet("line-regexp")) {
    regexp = "^" + regexp + "$";
} else {
    regexp = ".*" + regexp + ".*";
}

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

Create a file containing a long run of a characters:

printf 'aaaaaaaaaaaaaaaaaaaaaaa\n' > /tmp/testfile.txt

Run JLine3's built-in grep against that file:

grep '(a+)+b' /tmp/testfile.txt

Expected result: - The command stops responding. - The executing thread consumes high CPU.

Reproduction environment: - JLine3 on x86_64 Linux - OpenJDK 25.0.2

Impact

This is a denial-of-service vulnerability caused by catastrophic regex backtracking. Any application embedding org.jline:jline-builtins and exposing the built-in grep command is impacted. In remote shell deployments, an attacker can occupy a worker thread indefinitely and repeat the attack across multiple sessions to reduce service availability for other users.

Suggested Fix

The preferred fix for the current git head is: - stop rewriting non-line-regexp searches as .*...* - use Matcher.find() for substring semantics - compile user patterns with a linear-time engine such as RE2/J

Suggested patch:

diff --git a/builtins/pom.xml b/builtins/pom.xml
--- a/builtins/pom.xml
+++ b/builtins/pom.xml
@@
         <dependency>
+            <groupId>com.google.re2j</groupId>
+            <artifactId>re2j</artifactId>
+            <version>1.8</version>
+        </dependency>
+        <dependency>
             <groupId>org.jline</groupId>
             <artifactId>jline-reader</artifactId>
         </dependency>

diff --git a/builtins/src/main/java/org/jline/builtins/PosixCommands.java b/builtins/src/main/java/org/jline/builtins/PosixCommands.java
--- a/builtins/src/main/java/org/jline/builtins/PosixCommands.java
+++ b/builtins/src/main/java/org/jline/builtins/PosixCommands.java
@@
-import java.util.regex.Pattern;
+import com.google.re2j.Pattern;
@@
         if (opt.isSet("line-regexp")) {
             regexp = "^" + regexp + "$";
-        } else {
-            regexp = ".*" + regexp + ".*";
         }
@@
-        boolean m = p.matcher(line).matches();
+        boolean m = opt.isSet("line-regexp")
+                ? p.matcher(line).matches()
+                : p.matcher(line).find();

Credits

This issue was identified by Michał Majchrowicz and Marcin Wyczechowski, members of the AFINE Team.

Severity

7.5 (High)


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

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JSON

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.jline:jline-builtins"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "4.0.0"
            },
            {
              "fixed": "4.3.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "package": {
        "ecosystem": "Maven",
        "name": "org.jline:jline-builtins"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "3.0.0"
            },
            {
              "fixed": "3.30.15"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-77422"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-1333"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-09-23T18:12:35Z",
    "nvd_published_at": null,
    "severity": "HIGH"
  },
  "details": "### Summary\n\nThe JLine3 built-in `grep` command wraps the user-supplied regular expression with\n`.*` before compiling it with Java\u0027s backtracking regex engine. This amplifies\ncatastrophic backtracking and allows a short pattern such as `(a+)+b` to hang the\ncommand thread on non-matching input. In environments that expose the JLine shell to\nremote users, this is a denial-of-service issue.\n\n### Details\n\nIn `builtins/src/main/java/org/jline/builtins/PosixCommands.java`, the grep\nimplementation rewrites the user pattern before compilation:\n\n```java\nString regex = args.remove(0);\nString regexp = regex;\nif (opt.isSet(\"word-regexp\")) {\n    regexp = \"\\\\b\" + regexp + \"\\\\b\";\n}\nif (opt.isSet(\"line-regexp\")) {\n    regexp = \"^\" + regexp + \"$\";\n} else {\n    regexp = \".*\" + regexp + \".*\";\n}\n```\n\nThe transformed pattern is compiled with `Pattern.compile(...)` and then used to test\neach input line. For a payload such as `(a+)+b`, the automatic `.*` prefix and suffix\nincrease the backtracking search space substantially.\n\nAffected source location:\n- `builtins/src/main/java/org/jline/builtins/PosixCommands.java`\n- `grep(...)`\n\n### PoC\n\n1. Create a file containing a long run of `a` characters:\n\n```sh\nprintf \u0027aaaaaaaaaaaaaaaaaaaaaaa\\n\u0027 \u003e /tmp/testfile.txt\n```\n\n2. Run JLine3\u0027s built-in `grep` against that file:\n\n```sh\ngrep \u0027(a+)+b\u0027 /tmp/testfile.txt\n```\n\nExpected result:\n- The command stops responding.\n- The executing thread consumes high CPU.\n\nReproduction environment:\n- JLine3 on x86_64 Linux\n- OpenJDK 25.0.2\n\n### Impact\n\nThis is a denial-of-service vulnerability caused by catastrophic regex backtracking.\nAny application embedding `org.jline:jline-builtins` and exposing the built-in `grep`\ncommand is impacted. In remote shell deployments, an attacker can occupy a worker\nthread indefinitely and repeat the attack across multiple sessions to reduce service\navailability for other users.\n\n### Suggested Fix\n\nThe preferred fix for the current git head is:\n- stop rewriting non-line-regexp searches as `.*...*`\n- use `Matcher.find()` for substring semantics\n- compile user patterns with a linear-time engine such as RE2/J\n\nSuggested patch:\n\n```diff\ndiff --git a/builtins/pom.xml b/builtins/pom.xml\n--- a/builtins/pom.xml\n+++ b/builtins/pom.xml\n@@\n         \u003cdependency\u003e\n+            \u003cgroupId\u003ecom.google.re2j\u003c/groupId\u003e\n+            \u003cartifactId\u003ere2j\u003c/artifactId\u003e\n+            \u003cversion\u003e1.8\u003c/version\u003e\n+        \u003c/dependency\u003e\n+        \u003cdependency\u003e\n             \u003cgroupId\u003eorg.jline\u003c/groupId\u003e\n             \u003cartifactId\u003ejline-reader\u003c/artifactId\u003e\n         \u003c/dependency\u003e\n\ndiff --git a/builtins/src/main/java/org/jline/builtins/PosixCommands.java b/builtins/src/main/java/org/jline/builtins/PosixCommands.java\n--- a/builtins/src/main/java/org/jline/builtins/PosixCommands.java\n+++ b/builtins/src/main/java/org/jline/builtins/PosixCommands.java\n@@\n-import java.util.regex.Pattern;\n+import com.google.re2j.Pattern;\n@@\n         if (opt.isSet(\"line-regexp\")) {\n             regexp = \"^\" + regexp + \"$\";\n-        } else {\n-            regexp = \".*\" + regexp + \".*\";\n         }\n@@\n-        boolean m = p.matcher(line).matches();\n+        boolean m = opt.isSet(\"line-regexp\")\n+                ? p.matcher(line).matches()\n+                : p.matcher(line).find();\n```\n\n### Credits\n\nThis issue was identified by Micha\u0142 Majchrowicz and Marcin Wyczechowski, members of the AFINE Team.",
  "id": "GHSA-r2xf-8xr9-62gw",
  "modified": "2026-09-23T18:12:36Z",
  "published": "2026-09-23T18:12:35Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/security/advisories/GHSA-r2xf-8xr9-62gw"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/pull/2012"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/pull/2018"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/commit/341ee69ccc57b7733c1b40d6993219b64b3206ae"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/jline/jline3"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/releases/tag/4.3.1"
    },
    {
      "type": "WEB",
      "url": "https://github.com/jline/jline3/releases/tag/jline-3.30.15"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "JLine: ReDoS in Built-in grep Command Amplified by Automatic `.*` Wrapping"
}

CVE-2026-77422 (GCVE-0-2026-77422)

Vulnerability from cvelistv5 – Published: 2026-09-23 18:09 – Updated: 2026-09-24 14:13

Title

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

Summary

JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, the JLine built-in grep command in builtins/src/main/java/org/jline/builtins/PosixCommands.java accepts a user-controlled regular expression in grep(...) and, unless line-regexp mode is used, automatically adds a dot-star prefix and suffix before compiling it with Java's backtracking regular expression engine. The wrapping expands the backtracking search space, so a short nested-quantifier expression evaluated against non-matching input can consume excessive CPU and indefinitely block a command worker, including in remotely exposed shell sessions. This issue is fixed in versions 3.30.15 and 4.3.1.

Severity

7.5 (High)


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

SSVC

Exploitation: poc Automatable: yes Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-09-24 14:13 UTC

CWE

CWE-1333 - Inefficient Regular Expression Complexity

Assigner

GitHub_M mitre root

References

7 references

URL	Tags
https://github.com/jline/jline3/security/advisori…	x_refsource_CONFIRM
https://github.com/jline/jline3/pull/2012	x_refsource_MISC
https://github.com/jline/jline3/pull/2018	x_refsource_MISC
https://github.com/jline/jline3/commit/1d5fc3099e…	x_refsource_MISC
https://github.com/jline/jline3/commit/341ee69ccc…	x_refsource_MISC
https://github.com/jline/jline3/releases/tag/4.3.1	x_refsource_MISC
https://github.com/jline/jline3/releases/tag/jlin…	x_refsource_MISC

Impacted products

1 product

Vendor	Product	Version
jline	jline3	Affected: >= 3.0.0, < 3.30.15 Affected: >= 4.0.0, < 4.3.1

Show details on NVD website

JSON

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{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-77422",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-09-24T14:13:32.954382Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-09-24T14:13:39.588Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "references": [
          {
            "tags": [
              "exploit"
            ],
            "url": "https://github.com/jline/jline3/security/advisories/GHSA-r2xf-8xr9-62gw"
          }
        ],
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "product": "jline3",
          "vendor": "jline",
          "versions": [
            {
              "status": "affected",
              "version": "\u003e= 3.0.0, \u003c 3.30.15"
            },
            {
              "status": "affected",
              "version": "\u003e= 4.0.0, \u003c 4.3.1"
            }
          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "JLine is a Java library for handling console input. From 3.0.0 until 3.30.15 and 4.3.1, the JLine built-in grep command in builtins/src/main/java/org/jline/builtins/PosixCommands.java accepts a user-controlled regular expression in grep(...) and, unless line-regexp mode is used, automatically adds a dot-star prefix and suffix before compiling it with Java\u0027s backtracking regular expression engine. The wrapping expands the backtracking search space, so a short nested-quantifier expression evaluated against non-matching input can consume excessive CPU and indefinitely block a command worker, including in remotely exposed shell sessions. This issue is fixed in versions 3.30.15 and 4.3.1."
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "attackComplexity": "LOW",
            "attackVector": "NETWORK",
            "availabilityImpact": "HIGH",
            "baseScore": 7.5,
            "baseSeverity": "HIGH",
            "confidentialityImpact": "NONE",
            "integrityImpact": "NONE",
            "privilegesRequired": "NONE",
            "scope": "UNCHANGED",
            "userInteraction": "NONE",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
            "version": "3.1"
          }
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
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              "cweId": "CWE-1333",
              "description": "CWE-1333: Inefficient Regular Expression Complexity",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-09-23T18:09:32.308Z",
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      },
      "references": [
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          "name": "https://github.com/jline/jline3/security/advisories/GHSA-r2xf-8xr9-62gw",
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          ],
          "url": "https://github.com/jline/jline3/security/advisories/GHSA-r2xf-8xr9-62gw"
        },
        {
          "name": "https://github.com/jline/jline3/pull/2012",
          "tags": [
            "x_refsource_MISC"
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          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/jline/jline3/commit/1d5fc3099e77938b971e197211cad2d4fbb17541"
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        },
        {
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          ],
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        },
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          "name": "https://github.com/jline/jline3/releases/tag/jline-3.30.15",
          "tags": [
            "x_refsource_MISC"
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          "url": "https://github.com/jline/jline3/releases/tag/jline-3.30.15"
        }
      ],
      "source": {
        "advisory": "GHSA-r2xf-8xr9-62gw",
        "discovery": "UNKNOWN"
      },
      "title": "JLine: ReDoS in Built-in grep Command Amplified by Automatic `.*` Wrapping"
    }
  },
  "cveMetadata": {
    "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa",
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    "cveId": "CVE-2026-77422",
    "datePublished": "2026-09-23T18:09:32.308Z",
    "dateReserved": "2026-08-20T19:59:59.603Z",
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    "state": "PUBLISHED"
  },
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  "dataVersion": "5.2"
}

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

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Action not permitted

GHSA-R2XF-8XR9-62GW

Summary

Details

PoC

Impact

Suggested Fix

Credits

CVE-2026-77422 (GCVE-0-2026-77422)

Tags

Sightings

Nomenclature

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