diff --git a/.changeset/fix-overrides-value-validation.md b/.changeset/fix-overrides-value-validation.md
new file mode 100644
index 0000000000..2d44a7e8c0
--- /dev/null
+++ b/.changeset/fix-overrides-value-validation.md
@@ -0,0 +1,6 @@
+---
+"@pnpm/config.reader": patch
+"pnpm": patch
+---
+
+Throw a pnpm error when `overrides` has an invalid shape or contains a non-string value.
diff --git a/config/reader/src/getOptionsFromRootManifest.ts b/config/reader/src/getOptionsFromRootManifest.ts
index efdef766ab..ff3a45cbbf 100644
--- a/config/reader/src/getOptionsFromRootManifest.ts
+++ b/config/reader/src/getOptionsFromRootManifest.ts
@@ -28,6 +28,7 @@ export type OptionsFromRootManifest = {
 export function getOptionsFromPnpmSettings (manifestDir: string | undefined, pnpmSettings: PnpmSettings, manifest?: ProjectManifest): OptionsFromRootManifest {
   const settings: OptionsFromRootManifest = replaceEnvInSettings(pnpmSettings)
   if (settings.overrides) {
+    assertValidOverrides(settings.overrides)
     if (Object.keys(settings.overrides).length === 0) {
       delete settings.overrides
     } else if (manifest) {
@@ -45,6 +46,23 @@ export function getOptionsFromPnpmSettings (manifestDir: string | undefined, pnp
   return settings
 }
 
+function assertValidOverrides (overrides: unknown): asserts overrides is Record<string, string> {
+  if (overrides == null || typeof overrides !== 'object' || Array.isArray(overrides)) {
+    throw new PnpmError('INVALID_OVERRIDES', `The overrides field should be an object, but got ${renderReceivedType(overrides)}`)
+  }
+  for (const [selector, spec] of Object.entries(overrides)) {
+    if (typeof spec !== 'string') {
+      throw new PnpmError('INVALID_OVERRIDES', `The value of overrides.${selector} should be a string, but got ${renderReceivedType(spec)}`)
+    }
+  }
+}
+
+function renderReceivedType (value: unknown): string {
+  if (value === null) return 'null'
+  if (Array.isArray(value)) return 'array'
+  return typeof value
+}
+
 function replaceEnvInSettings (settings: PnpmSettings): PnpmSettings {
   const newSettings: PnpmSettings = {}
   for (const [key, value] of Object.entries(settings)) {
diff --git a/config/reader/test/getOptionsFromRootManifest.test.ts b/config/reader/test/getOptionsFromRootManifest.test.ts
index 43f63ff6ea..10cf161662 100644
--- a/config/reader/test/getOptionsFromRootManifest.test.ts
+++ b/config/reader/test/getOptionsFromRootManifest.test.ts
@@ -33,3 +33,34 @@ test('getOptionsFromPnpmSettings() converts allowBuilds', () => {
     },
   })
 })
+
+test('getOptionsFromPnpmSettings() rejects non-string overrides values', () => {
+  expect(() => getOptionsFromPnpmSettings(process.cwd(), {
+    overrides: {
+      foo: null,
+    } as unknown as Record<string, string>,
+  })).toThrow(expect.objectContaining({
+    code: 'ERR_PNPM_INVALID_OVERRIDES',
+    message: 'The value of overrides.foo should be a string, but got null',
+  }))
+})
+
+test('getOptionsFromPnpmSettings() rejects array overrides values', () => {
+  expect(() => getOptionsFromPnpmSettings(process.cwd(), {
+    overrides: {
+      foo: [],
+    } as unknown as Record<string, string>,
+  })).toThrow(expect.objectContaining({
+    code: 'ERR_PNPM_INVALID_OVERRIDES',
+    message: 'The value of overrides.foo should be a string, but got array',
+  }))
+})
+
+test('getOptionsFromPnpmSettings() rejects non-object overrides values', () => {
+  expect(() => getOptionsFromPnpmSettings(process.cwd(), {
+    overrides: [] as unknown as Record<string, string>,
+  })).toThrow(expect.objectContaining({
+    code: 'ERR_PNPM_INVALID_OVERRIDES',
+    message: 'The overrides field should be an object, but got array',
+  }))
+})