CVE-2021-23900 (published 2021-01-13T16:15Z)

OWASP json-sanitizer before 1.2.2 can output invalid JSON or throw an undeclared exception for crafted input. This may lead to denial of service if the application is not prepared to handle these situations.

Severity: MEDIUM
CVSS v2 base score: 5.0 (AV:N/AC:L/Au:N/C:N/I:N/A:P)
CVSS v3 base score: 7.5, HIGH (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H)

Weakness information:
cwe_id: NVD-CWE-noinfo
cwe_name: Insufficient Information
description: There is insufficient information about the issue to classify it; details are unkown or unspecified.
extended_description: Insufficient Information

Fix information:
repo_url: https://github.com/OWASP/json-sanitizer
commit_details: repo_url: https://github.com/OWASP/json-sanitizer
author: Mike Samuel
author_date: 2021-01-12 17:31:19-05:00
msg: Tests for fixes for previously undisclosed vulnerabilities

These include tests that reproduced fuzzer findings cqommunicated
privately by Fabian Meumertzheim of codeintelligence.

They were held back, separate from the fixes, until a release had time
to propagate.

Public disclosure at
https://groups.google.com/g/json-sanitizer-support/c/dAW1AeNMoA0
repository: repo_url: https://github.com/OWASP/json-sanitizer
repo_name: OWASP/json-sanitizer
description: Given JSON-like content, The JSON Sanitizer converts it to valid JSON.
repo_language: Java
owner: OWASP
file_changes: filename: FuzzyTest.java
change_type: ModificationType.MODIFY
diff: @@ -62,6 +62,32 @@ public final class FuzzyTest extends TestCase {
         String sanitized0 = JsonSanitizer.sanitize(fuzzyWuzzyString);
         String sanitized1 = JsonSanitizer.sanitize(sanitized0);
         // Test idempotence.
+        if (!sanitized0.equals(sanitized1)) {
+          int commonPrefixLen = 0;
+          int minLength = Math.min(sanitized0.length(), sanitized1.length());
+          while (commonPrefixLen < minLength) {
+            if (sanitized0.charAt(commonPrefixLen) != sanitized1.charAt(commonPrefixLen)) {
+              break;
+            }
+            ++commonPrefixLen;
+          }
+
+          int right0 = sanitized0.length();
+          int right1 = sanitized1.length();
+          while (right0 > commonPrefixLen && right1 > commonPrefixLen) {
+            if (sanitized0.charAt(right0 - 1) != sanitized1.charAt(right1 - 1)) {
+              break;
+            }
+            --right0;
+            --right1;
+          }
+
+          int commonSuffixLen = sanitized0.length() - right0;
+
+          System.err.println("Difference at " + commonPrefixLen + " to -" + commonSuffixLen);
+          System.err.println("Before: " + excerpt(sanitized0, commonPrefixLen, right0));
+          System.err.println("After:  " + excerpt(sanitized0, commonPrefixLen, right1));
+        }
         assertEquals(fuzzyWuzzyString + "  =>  " + sanitized0, sanitized0,
                      sanitized1);
       } catch (Throwable th) {
@@ -90,6 +116,23 @@ public final class FuzzyTest extends TestCase {
       app.append("0123456789ABCDEF".charAt((b >>> 0) & 0xf));
     }
   }
+
+  private static String excerpt(String s, int left, int right) {
+    int leftIncl = left - 10;
+    boolean ellipseLeft = leftIncl > 0;
+    if (!ellipseLeft) { leftIncl = 0; }
+
+    int rightIncl = right + 10;
+    boolean ellipseRight = s.length() > rightIncl;
+    if (!ellipseRight) {
+      rightIncl = s.length();
+    }
+
+    return s.substring(leftIncl, rightIncl)
+            .replace("\r", "\\r")
+            .replace("\n", "\\n")
+            .replace("\\", "\\\\");
+  }
 }
 
 final class FuzzyStringGenerator implements Iterable<String> {

programming_language: Java
filename: JsonSanitizerTest.java
change_type: ModificationType.MODIFY
diff: @@ -16,6 +16,8 @@ package com.google.json;
 
 import static com.google.json.JsonSanitizer.DEFAULT_NESTING_DEPTH;
 import static com.google.json.JsonSanitizer.sanitize;
+
+import java.util.Locale;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import junit.framework.TestCase;
@@ -198,7 +200,7 @@ public final class JsonSanitizerTest extends TestCase {
   }
 
   @Test
-  public static final void testClosedArray() {
+  public static final void testUnopenedArray() {
     // Discovered by fuzzer with seed -Dfuzz.seed=df3b4778ce54d00a
     assertSanitized("-1742461140214282", "\ufeff-01742461140214282]");
   }
@@ -228,4 +230,102 @@ public final class JsonSanitizerTest extends TestCase {
 
     assertSanitized("\"\\u003c!--\\u003cscript>\"", "\"<!--<script>\"");
   }
+
+  @Test
+  public static final void testLongOctalNumberWithBadDigits() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    assertEquals(
+            "-888888888888888888888",
+            JsonSanitizer.sanitize("-0888888888888888888888")
+    );
+  }
+
+  @Test
+  public static final void testLongNumberInUnclosedInputWithU80() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    assertEquals(
+            "{\"\":{\"\":{\"\":{\"\":{\"\":{\"\":{\"x80\":{\"\":{\"\":[-400557869725698078427]}}}}}}}}}",
+            JsonSanitizer.sanitize("{{{{{{{\\x80{{([-053333333304233333333333")
+    );
+  }
+
+  @Test
+  public static final void testSlashFour() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    assertEquals("\"y\\u0004\"", JsonSanitizer.sanitize("y\\4")); // "y\4"
+  }
+
+  @Test
+  public static final void testUnterminatedObject() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    String input = "?\u0000\u0000\u0000{{\u0000\ufffd\u0003]ve{R]\u00000\ufffd\u0016&e{\u0003]\ufffda<!.b<!<!cc1x\u0000\u00005{281<\u0000.{t\u0001\ufffd5\ufffd{5\ufffd\ufffd0\ufffd15\r\ufffd\u0000\u0000\u0000~~-0081273222428822883223759,55\ufffd\u0000\ufffd\t\u0000\ufffd";
+    String got = JsonSanitizer.sanitize(input);
+    String want = "{\"\":{},\"ve\":{\"R\":null},\"0\":\"e\",\"\":{},\"a<!.b<!<!cc1x\":5,\"\":{\"281\":0.0,\"\":{\"t\":5,\"\":{\"5\":0,\"15\"\r:-81273222428822883223759,\"55\"\t:null}}}}";
+    assertEquals(want, got);
+  }
+
+  @Test
+  public static final void testCrash1() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    String input = "?\u0000\u0000\u0000{{\u0000\ufffd\u0003]ve{R]\u00000\ufffd\ufffd\u0016&e{\u0003]\ufffda<!.b<!<!c\u00005{281<\u0000.{t\u0001\ufffd5\ufffd{515\r[\u0000\u0000\u0000~~-008127322242\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd\ufffd23759,551x\u0000\u00006{281<\u0000.{t\u0001\ufffd5\ufffd{5\ufffd\ufffd0\ufffd15\r[\u0000\u0000\u0000~~-0081273222428822883223759,\ufffd";
+    String want = "{\"\":{},\"ve\":{\"R\":null},\"0\":\"e\",\"\":{},\"a<!.b<!<!c\":5,\"\":{\"281\":0.0,\"\":{\"t\":5,\"\":{\"515\"\r:[-8127322242,23759,551,6,{\"281\":0.0,\"\":{\"t\":5,\"\":{\"5\":0,\"15\"\r:[-81273222428822883223759]}}}]}}}}";
+    String got = JsonSanitizer.sanitize(input);
+    assertEquals(want, got);
+  }
+
+  @Test
+  public static final void testDisallowedSubstrings() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    String[] inputs = {
+            "x<\\script>",
+            "x</\\script>",
+            "x</sc\\ript>",
+            "x<\\163cript>",
+            "x</\\163cript>",
+            "x<\\123cript>",
+            "x</\\123cript>",
+            "u\\u\\uu\ufffd\ufffd\\u7u\\u\\u\\u\ufffdu<\\script>5",
+            "z\\<\\!--",
+            "z\\<!\\--",
+            "z\\<!-\\-",
+            "z\\<\\!--",
+            "\"\\]]\\>",
+    };
+    for (String input : inputs) {
+      String out = JsonSanitizer.sanitize(input).toLowerCase(Locale.ROOT);
+      assertFalse(out, out.contains("<!--"));
+      assertFalse(out, out.contains("-->"));
+      assertFalse(out, out.contains("<script"));
+      assertFalse(out, out.contains("</script"));
+      assertFalse(out, out.contains("]]>"));
+      assertFalse(out, out.contains("<![cdata["));
+    }
+  }
+
+  @Test
+  public static final void testXssPayload() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    String input = "x</\\script>u\\u\\uu\ufffd\ufffd\\u7u\\u\\u\\u\ufffdu<\\script>5+alert(1)//";
+    assertEquals(
+            "\"x\\u003c/script>uuuu\uFFFD\uFFFDu7uuuu\uFFFDu\\u003cscript>5+alert(1)//\"",
+            JsonSanitizer.sanitize(input)
+    );
+  }
+
+  @Test
+  public static final void testInvalidOutput() {
+    // Found by Fabian Meumertzheim using CI Fuzz (https://www.code-intelligence.com)
+    String input = "\u0010{'\u0000\u0000'\"\u0000\"{.\ufffd-0X29295909049550970,\n\n0";
+    String want = "{\"\\u0000\\u0000\":\"\\u0000\",\"\":{\"0\":-47455995597866469744,\n\n\"0\":null}}";
+    String got = JsonSanitizer.sanitize(input);
+    assertEquals(want, got);
+  }
+
+  @Test
+  public static final void testBadNumber() {
+    String input = "¶0x.\\蹃4\\À906";
+    String want = "0.0";
+    String got = JsonSanitizer.sanitize(input);
+    assertEquals(want, got);
+  }
 }

programming_language: Java