diff --git a/csaf_2_1/mandatoryTests.js b/csaf_2_1/mandatoryTests.js
index 9b5b19a..18eea4a 100644
--- a/csaf_2_1/mandatoryTests.js
+++ b/csaf_2_1/mandatoryTests.js
@@ -44,3 +44,4 @@ export {
   mandatoryTest_6_1_33,
 } from '../mandatoryTests.js'
 export { mandatoryTest_6_1_34 } from './mandatoryTests/mandatoryTest_6_1_34.js'
+export { mandatoryTest_6_1_35 } from './mandatoryTests/mandatoryTest_6_1_35.js'
diff --git a/csaf_2_1/mandatoryTests/mandatoryTest_6_1_35.js b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_35.js
new file mode 100644
index 0000000..b74c95f
--- /dev/null
+++ b/csaf_2_1/mandatoryTests/mandatoryTest_6_1_35.js
@@ -0,0 +1,209 @@
+import Ajv from 'ajv/dist/jtd.js'
+
+const ajv = new Ajv()
+
+/**
+ * @typedef {'workaround'
+ *  | 'mitigation'
+ *  | 'vendor_fix'
+ *  | 'optional_patch'
+ *  | 'none_available'
+ *  | 'fix_planned'
+ *  | 'no_fix_planned'} Category
+ */
+
+/**
+ * This map holds prohibited category combinations.
+ * See https://github.com/oasis-tcs/csaf/blob/master/csaf_2.1/prose/share/csaf-v2.1-draft.md#324131-vulnerabilities-property---remediations---category-
+ *
+ * @type {Map<string, Set<string>>}
+ */
+const prohibitionRuleMap = new Map(
+  /** @satisfies {Array<[Category, Category[]]>} */ ([
+    ['workaround', ['optional_patch', 'none_available']],
+    ['mitigation', ['optional_patch', 'none_available']],
+    [
+      'vendor_fix',
+      ['optional_patch', 'none_available', 'fix_planned', 'no_fix_planned'],
+    ],
+    [
+      'optional_patch',
+      [
+        'workaround',
+        'mitigation',
+        'vendor_fix',
+        'none_available',
+        'fix_planned',
+        'no_fix_planned',
+      ],
+    ],
+    [
+      'none_available',
+      [
+        'workaround',
+        'mitigation',
+        'vendor_fix',
+        'optional_patch',
+        'fix_planned',
+        'no_fix_planned',
+      ],
+    ],
+    [
+      'fix_planned',
+      ['vendor_fix', 'optional_patch', 'none_available', 'no_fix_planned'],
+    ],
+    [
+      'no_fix_planned',
+      ['vendor_fix', 'optional_patch', 'none_available', 'fix_planned'],
+    ],
+  ]).map((e) => [e[0], new Set(e[1])])
+)
+
+const remediationSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    group_ids: {
+      elements: {
+        type: 'string',
+      },
+    },
+    product_ids: {
+      elements: {
+        type: 'string',
+      },
+    },
+    category: { type: 'string' },
+  },
+})
+
+/*
+  This is the jtd schema that needs to match the input document so that the
+  test is activated. If this schema doesn't match it normally means that the input
+  document does not validate against the csaf json schema or optional fields that
+  the test checks are not present.
+ */
+const inputSchema = /** @type {const} */ ({
+  additionalProperties: true,
+  optionalProperties: {
+    product_tree: {
+      additionalProperties: true,
+      optionalProperties: {
+        product_groups: {
+          elements: {
+            additionalProperties: true,
+            optionalProperties: {
+              group_id: { type: 'string' },
+              product_ids: {
+                elements: {
+                  type: 'string',
+                },
+              },
+            },
+          },
+        },
+      },
+    },
+  },
+  properties: {
+    vulnerabilities: {
+      elements: {
+        additionalProperties: true,
+        optionalProperties: {
+          remediations: {
+            elements: remediationSchema,
+          },
+        },
+      },
+    },
+  },
+})
+
+const validate = ajv.compile(inputSchema)
+
+/**
+ * This implements the mandatory test of the CSAF 2.1 standard.
+ *
+ * @param {any} doc
+ */
+export function mandatoryTest_6_1_35(doc) {
+  /*
+    The `ctx` variable holds the state that is accumulated during the test ran and is
+    finally returned by the function.
+   */
+  const ctx = {
+    /** @type {Array<{ instancePath: string; message: string }>} */
+    errors: [],
+    isValid: true,
+  }
+
+  if (!validate(doc)) {
+    return ctx
+  }
+
+  for (const [vulnerabilityIndex, vulnerability] of Object.entries(
+    doc.vulnerabilities
+  )) {
+    /**
+     * This map holds all discovered product ids and maps them to the set of corresponding
+     * remediation categories. Later we can check this map to find out if there are any
+     * contradicting remediations.
+     *
+     * @type {Map<string, Set<string>>}
+     */
+    const productToCategoriesMap = new Map()
+
+    vulnerability.remediations?.forEach((remediation, remediationIndex) => {
+      const category = remediation.category
+      if (!category) return
+
+      /**
+       * This function adds the current category to the given product id in the
+       * `productMap`. If the product does not yet exist in the map, it is added.
+       *
+       * @param {string} id
+       */
+      const collectCategory = (id) => {
+        productToCategoriesMap.set(
+          id,
+          new Set(productToCategoriesMap.get(id)).add(category)
+        )
+      }
+
+      remediation.product_ids?.forEach(collectCategory)
+
+      remediation.group_ids?.forEach((id) => {
+        const group = doc.product_tree?.product_groups?.find(
+          (g) => g.group_id === id
+        )
+        if (!group) return
+        group.product_ids?.forEach(collectCategory)
+      })
+
+      for (const [productId, categories] of productToCategoriesMap) {
+        /**
+         * This set will hold all already checked categories to avoid double checks
+         * and doubled error messages.
+         */
+        const checkedCategories = new Set()
+
+        for (const categoryA of categories) {
+          checkedCategories.add(categoryA)
+
+          for (const categoryB of categories) {
+            if (checkedCategories.has(categoryB)) continue
+
+            if (prohibitionRuleMap.get(categoryA)?.has(categoryB)) {
+              ctx.errors.push({
+                instancePath: `/vulnerabilities/${vulnerabilityIndex}/remediations/${remediationIndex}`,
+                message: `contradicting remediation categories for product id "${productId}": ${categoryA}, ${categoryB}`,
+              })
+              ctx.isValid = false
+            }
+          }
+        }
+      }
+    })
+  }
+
+  return ctx
+}
diff --git a/tests/csaf_2_1/mandatoryTest_6_1_35.js b/tests/csaf_2_1/mandatoryTest_6_1_35.js
new file mode 100644
index 0000000..13da145
--- /dev/null
+++ b/tests/csaf_2_1/mandatoryTest_6_1_35.js
@@ -0,0 +1,35 @@
+import assert from 'node:assert'
+import { mandatoryTest_6_1_35 } from '../../csaf_2_1/mandatoryTests.js'
+
+describe('mandatoryTest_6_1_37', function () {
+  it('only runs on relevant documents', function () {
+    assert.equal(mandatoryTest_6_1_35({ document: 'mydoc' }).isValid, true)
+  })
+
+  it('skips remediations without valid category', function () {
+    assert.equal(
+      mandatoryTest_6_1_35({
+        vulnerabilities: [{ remediations: [{}] }],
+      }).isValid,
+      true
+    )
+  })
+
+  it('skips remediation group checks without declared group', function () {
+    assert.equal(
+      mandatoryTest_6_1_35({
+        vulnerabilities: [
+          {
+            remediations: [
+              {
+                category: 'some_category',
+                group_ids: ['my_not_existing_group'],
+              },
+            ],
+          },
+        ],
+      }).isValid,
+      true
+    )
+  })
+})
diff --git a/tests/csaf_2_1/oasis.js b/tests/csaf_2_1/oasis.js
index e3bb154..c5c791f 100644
--- a/tests/csaf_2_1/oasis.js
+++ b/tests/csaf_2_1/oasis.js
@@ -18,7 +18,6 @@ const excluded = [
   '6.1.13',
   '6.1.14',
   '6.1.16',
-  '6.1.35',
   '6.1.36',
   '6.1.37',
   '6.1.38',