diff --git a/src/core/plugins/deep-linking/helpers.js b/src/core/plugins/deep-linking/helpers.js
index d06bbe27dc1..ccfef08d8d0 100644
--- a/src/core/plugins/deep-linking/helpers.js
+++ b/src/core/plugins/deep-linking/helpers.js
@@ -1,6 +1,11 @@
 export const setHash = (value) => {
   if(value) {
-    return history.pushState(null, null, `#${value}`)
+    // Include the current pathname and search explicitly so that a
+    // document-level `<base href>` (set by frameworks like Angular) does not
+    // cause `pushState` to resolve `#value` against the base URL and replace
+    // the current route. See https://github.com/swagger-api/swagger-ui/issues/10591
+    const { pathname, search } = window.location
+    return history.pushState(null, null, `${pathname}${search}#${value}`)
   } else {
     return window.location.hash = ""
   }
diff --git a/test/e2e-cypress/e2e/bugs/10591.cy.js b/test/e2e-cypress/e2e/bugs/10591.cy.js
new file mode 100644
index 00000000000..3b946027315
--- /dev/null
+++ b/test/e2e-cypress/e2e/bugs/10591.cy.js
@@ -0,0 +1,33 @@
+describe("#10591: deep-linking with document <base href> should not replace current route", () => {
+  const baseUrl = "/?deepLinking=true&url=/documents/features/deep-linking.openapi.yaml"
+
+  it("should preserve the page pathname and search when an operation is expanded", () => {
+    cy.intercept(
+      {
+        method: "GET",
+        pathname: "/",
+      },
+      (req) => {
+        req.continue((res) => {
+          if (typeof res.body === "string" && res.body.includes("</head>")) {
+            res.body = res.body.replace("</head>", "<base href=\"/\">\n</head>")
+          }
+        })
+      }
+    ).as("indexHtml")
+
+    cy.visit(baseUrl)
+    cy.wait("@indexHtml")
+    cy.get(".opblock-get").first().click()
+
+    cy.location().should((loc) => {
+      // The URL hash must change to reflect the deep link...
+      expect(loc.hash).to.not.equal("")
+      // ...but the pathname (and search) must NOT have been replaced by the
+      // browser resolving "#..." against the document <base href="/">.
+      expect(loc.pathname).to.equal("/")
+      expect(loc.search).to.contain("deepLinking=true")
+      expect(loc.search).to.contain("url=/documents/features/deep-linking.openapi.yaml")
+    })
+  })
+})
diff --git a/test/unit/core/plugins/deep-linking/helpers.js b/test/unit/core/plugins/deep-linking/helpers.js
new file mode 100644
index 00000000000..ea866b66612
--- /dev/null
+++ b/test/unit/core/plugins/deep-linking/helpers.js
@@ -0,0 +1,63 @@
+/**
+ * @prettier
+ */
+import { setHash } from "core/plugins/deep-linking/helpers"
+
+describe("deep-linking plugin - helpers", () => {
+  describe("setHash", () => {
+    let originalLocation
+    let pushStateSpy
+
+    beforeEach(() => {
+      originalLocation = window.location
+      pushStateSpy = jest
+        .spyOn(window.history, "pushState")
+        .mockImplementation(() => {})
+    })
+
+    afterEach(() => {
+      pushStateSpy.mockRestore()
+      Object.defineProperty(window, "location", {
+        configurable: true,
+        value: originalLocation,
+      })
+    })
+
+    const stubLocation = (pathname, search) => {
+      Object.defineProperty(window, "location", {
+        configurable: true,
+        value: { ...originalLocation, pathname, search, hash: "" },
+      })
+    }
+
+    it("should preserve the current pathname and search when pushing a hash", () => {
+      stubLocation("/app/api-docs", "?env=staging")
+
+      setHash("/myTag/myOperation")
+
+      expect(pushStateSpy).toHaveBeenCalledWith(
+        null,
+        null,
+        "/app/api-docs?env=staging#/myTag/myOperation"
+      )
+    })
+
+    it("should still push a hash when the current URL has no search string", () => {
+      stubLocation("/swagger", "")
+
+      setHash("/foo")
+
+      expect(pushStateSpy).toHaveBeenCalledWith(null, null, "/swagger#/foo")
+    })
+
+    it("should clear window.location.hash when called with an empty value", () => {
+      stubLocation("/swagger", "")
+      window.location.hash = "#/foo"
+
+      setHash("")
+
+      expect(window.location.hash).toBe("")
+      expect(pushStateSpy).not.toHaveBeenCalled()
+    })
+  })
+})