From a3323de5da924215c8ae9710e4fc684d4f9af2e1 Mon Sep 17 00:00:00 2001
From: Napster <napster@npstr.space>
Date: Tue, 13 Feb 2024 16:59:42 +0100
Subject: [PATCH] Handle trailing semicolon when parsing Accept-Language header

---
 .../java/org/springframework/http/HttpHeaders.java  |  3 +++
 .../org/springframework/http/HttpHeadersTests.java  | 13 +++++++++++++
 2 files changed, 16 insertions(+)

diff --git a/spring-web/src/main/java/org/springframework/http/HttpHeaders.java b/spring-web/src/main/java/org/springframework/http/HttpHeaders.java
index d1656fbf843d..5e16013e1723 100644
--- a/spring-web/src/main/java/org/springframework/http/HttpHeaders.java
+++ b/spring-web/src/main/java/org/springframework/http/HttpHeaders.java
@@ -502,6 +502,9 @@ public void setAcceptLanguage(List<Locale.LanguageRange> languages) {
 	 */
 	public List<Locale.LanguageRange> getAcceptLanguage() {
 		String value = getFirst(ACCEPT_LANGUAGE);
+		if (value != null) {
+			value = StringUtils.trimTrailingCharacter(value, ';');
+		}
 		return (StringUtils.hasText(value) ? Locale.LanguageRange.parse(value) : Collections.emptyList());
 	}
 
diff --git a/spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java b/spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java
index 18696a7a1609..a95bdc6c9dce 100644
--- a/spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java
+++ b/spring-web/src/test/java/org/springframework/http/HttpHeadersTests.java
@@ -489,6 +489,19 @@ void acceptLanguage() {
 		assertThat(headers.getAcceptLanguageAsLocales()).element(0).isEqualTo(Locale.FRANCE);
 	}
 
+	@Test
+	void acceptLanguageTrailingSemicolon() {
+		String headerValue = "en-us,en;";
+		headers.set(HttpHeaders.ACCEPT_LANGUAGE, headerValue);
+		assertThat(headers.getFirst(HttpHeaders.ACCEPT_LANGUAGE)).isEqualTo(headerValue);
+
+		List<Locale.LanguageRange> expectedRanges = Arrays.asList(
+				new Locale.LanguageRange("en-us"),
+				new Locale.LanguageRange("en")
+		);
+		assertThat(headers.getAcceptLanguage()).isEqualTo(expectedRanges);
+	}
+
 	@Test // SPR-15603
 	void acceptLanguageWithEmptyValue() {
 		this.headers.set(HttpHeaders.ACCEPT_LANGUAGE, "");