diff --git a/CHANGELOG.md b/CHANGELOG.md
index ac2ac8d83..338a78eb9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -32,6 +32,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Don't generate utilities when a modifier is used that would otherwise be silently ignored (e.g. `rounded-sm/[5]`, `shadow-sm/foo`, `stroke-2/50`) ([#20419](https://github.com/tailwindlabs/tailwindcss/pull/20419))
 - Only normalize top-level `and`, `or`, and `not` keywords in `supports-[…]` variants (e.g. `selector(a: not (.foo))` → `selector(a:not(.foo))`) ([#20420](https://github.com/tailwindlabs/tailwindcss/pull/20420))
 - Don't warn about Angular's `::ng-deep` and `:host-context()` when optimizing CSS ([#20434](https://github.com/tailwindlabs/tailwindcss/pull/20434))
+- Don't generate CSS for candidates containing an empty additional modifier (e.g. `bg-red-500/50/` and `group-hover/foo//bar:flex`) ([#20466](https://github.com/tailwindlabs/tailwindcss/pull/20466))
 
 ## [4.3.3] - 2026-07-16
 
diff --git a/packages/tailwindcss/src/candidate.test.ts b/packages/tailwindcss/src/candidate.test.ts
index d66bfcd66..b8f914e1b 100644
--- a/packages/tailwindcss/src/candidate.test.ts
+++ b/packages/tailwindcss/src/candidate.test.ts
@@ -516,6 +516,8 @@ it('should not parse functional utilities with multiple modifiers', () => {
   utilities.functional('bg', () => [])
 
   expect(run('bg-red-1/2/3', { utilities })).toMatchInlineSnapshot(`[]`)
+  expect(run('bg-red-500/50/', { utilities })).toMatchInlineSnapshot(`[]`)
+  expect(run('bg-red-500/50//foo', { utilities })).toMatchInlineSnapshot(`[]`)
 })
 
 it('should parse a utility with an arbitrary value', () => {
@@ -1416,6 +1418,19 @@ it('should parse a functional variant with a modifier', () => {
   `)
 })
 
+it('should not parse variants with multiple modifiers', () => {
+  let utilities = new Utilities()
+  utilities.static('flex', () => [])
+
+  let variants = new Variants()
+  variants.static('hover', () => {})
+  variants.compound('group', Compounds.StyleRules, () => {})
+
+  expect(run('group-hover/foo:flex', { utilities, variants })).toHaveLength(1)
+  expect(run('group-hover/foo/:flex', { utilities, variants })).toEqual([])
+  expect(run('group-hover/foo//bar:flex', { utilities, variants })).toEqual([])
+})
+
 it('should parse a functional variant starting with @', () => {
   let utilities = new Utilities()
   utilities.static('flex', () => [])
diff --git a/packages/tailwindcss/src/candidate.ts b/packages/tailwindcss/src/candidate.ts
index b63588ce7..b4a5988e0 100644
--- a/packages/tailwindcss/src/candidate.ts
+++ b/packages/tailwindcss/src/candidate.ts
@@ -372,6 +372,14 @@ export function* parseCandidate(input: string, designSystem: DesignSystem): Iter
     }
   }
 
+  // If there's more than one modifier, the utility is invalid.
+  //
+  // E.g.:
+  //
+  // - `bg-red-500/50/50`
+  let parts = segment(base, '/')
+  if (parts.length > 2) return
+
   // Figure out the new base and the modifier segment if present.
   //
   // E.g.:
@@ -381,14 +389,7 @@ export function* parseCandidate(input: string, designSystem: DesignSystem): Iter
   // ^^^^^^^^^^    -> Base without modifier
   //            ^^ -> Modifier segment
   // ```
-  let [baseWithoutModifier, modifierSegment = null, additionalModifier] = segment(base, '/')
-
-  // If there's more than one modifier, the utility is invalid.
-  //
-  // E.g.:
-  //
-  // - `bg-red-500/50/50`
-  if (additionalModifier) return
+  let [baseWithoutModifier, modifierSegment = null] = parts
 
   let parsedModifier = modifierSegment === null ? null : parseModifier(modifierSegment)
 
@@ -707,17 +708,18 @@ export function parseVariant(variant: string, designSystem: DesignSystem): Varia
 
   // Static, functional and compound variants
   {
-    // group-hover/group-name
-    // ^^^^^^^^^^^            -> Variant without modifier
-    //             ^^^^^^^^^^ -> Modifier
-    let [variantWithoutModifier, modifier = null, additionalModifier] = segment(variant, '/')
-
     // If there's more than one modifier, the variant is invalid.
     //
     // E.g.:
     //
     // - `group-hover/foo/bar`
-    if (additionalModifier) return null
+    let parts = segment(variant, '/')
+    if (parts.length > 2) return null
+
+    // group-hover/group-name
+    // ^^^^^^^^^^^            -> Variant without modifier
+    //             ^^^^^^^^^^ -> Modifier
+    let [variantWithoutModifier, modifier = null] = parts
 
     let roots = findRoots(variantWithoutModifier, (root) => {
       return designSystem.variants.has(root)