[JENKINS-72412] Overmasking when trivial “secrets” bound

src/main/java/org/jenkinsci/plugins/credentialsbinding/masking/SecretPatterns.java

@@ -44,6 +44,12 @@ public class SecretPatterns {
     private static final Comparator<String> BY_LENGTH_DESCENDING =
             Comparator.comparingInt(String::length).reversed().thenComparing(String::compareTo);
 
+    /**
+     * Masking (encoded) “secrets” shorter than this would just be ridiculous.
+     * Particularly relevant with {@link Base64SecretPatternFactory}.
+     */
+    private static final int MINIMUM_ENCODED_LENGTH = 3;
+
     /**
      * Constructs a regular expression to match against all known forms that the given collection of input strings may
      * appear. This pattern is optimized such that longer masks are checked before shorter masks. By doing so, this
@@ -61,6 +67,7 @@ public class SecretPatterns {
                 .flatMap(input ->
                         secretPatternFactories.stream().flatMap(factory ->
                                 factory.getEncodedForms(input).stream()))
+                .filter(encoded -> encoded.length() >= MINIMUM_ENCODED_LENGTH)
                 .sorted(BY_LENGTH_DESCENDING)
                 .distinct()
                 .map(Pattern::quote)

src/test/java/org/jenkinsci/plugins/credentialsbinding/impl/BindingStepTest.java

@@ -321,6 +321,25 @@ public void widerRequiredContext() throws Throwable {
         });
     }
 
+    @Issue("JENKINS-72412")
+    @Test public void maskingOfOneCharSecretShouldNotMangleOutput() throws Throwable {
+        rr.then(r -> {
+            String credentialsId = "creds";
+            String secret = "a";
+            CredentialsProvider.lookupStores(r.jenkins).iterator().next().addCredentials(Domain.global(), new StringCredentialsImpl(CredentialsScope.GLOBAL, credentialsId, "sample", Secret.fromString(secret)));
+            WorkflowJob p = r.jenkins.createProject(WorkflowJob.class, "p");
+            p.setDefinition(new CpsFlowDefinition(""
+                + "node {\n"
+                + "  withCredentials([string(credentialsId: '" + credentialsId + "', variable: 'SECRET')]) {\n"
+                // forgot set +x, ran /usr/bin/env, etc.
+                + "    if (isUnix()) {sh 'echo $SECRET > oops'} else {bat 'echo %SECRET% > oops'}\n"
+                + "  }\n"
+                + "}", true));
+            WorkflowRun b = r.assertBuildStatusSuccess(p.scheduleBuild2(0).get());
+            r.assertLogContains("echo", b);
+        });
+    }
+
     @Issue("JENKINS-30326")
     @Test
     public void testGlobalBindingWithAuthorization() throws Throwable {