diff --git a/CHANGELOG.md b/CHANGELOG.md
index 169cb6093..b68a9e1d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ Only write entries that are worth mentioning to users.
 
 ## Unreleased
 
+- Core: Fix HTTP header values containing trailing whitespace/newlines on certain Linux systems (e.g. kernel 6.8.0-101) causing connection errors — strip whitespace from ASCII header values before sending
 - Core: Fix OpenAI Responses provider sending implicit `reasoning.effort=null` which breaks Responses-compatible endpoints that require reasoning — reasoning parameters are now omitted unless explicitly set
 - Core: Fix context compaction failing when conversation contains media parts (images, audio, video) — switch from blacklist filtering (exclude `ThinkPart`) to whitelist filtering (only keep `TextPart`) to prevent unsupported content types from being sent to the compaction API
 - Web: Fix `@` file mention index not refreshing after switching sessions or when workspace files change — reset index on session switch, auto-refresh after 30s staleness, and support path-prefix search beyond the 500-file limit
diff --git a/docs/en/release-notes/changelog.md b/docs/en/release-notes/changelog.md
index 361a6609e..0fb7aa999 100644
--- a/docs/en/release-notes/changelog.md
+++ b/docs/en/release-notes/changelog.md
@@ -4,6 +4,7 @@ This page documents the changes in each Kimi Code CLI release.
 
 ## Unreleased
 
+- Core: Fix HTTP header values containing trailing whitespace/newlines on certain Linux systems (e.g. kernel 6.8.0-101) causing connection errors — strip whitespace from ASCII header values before sending
 - Core: Fix OpenAI Responses provider sending implicit `reasoning.effort=null` which breaks Responses-compatible endpoints that require reasoning — reasoning parameters are now omitted unless explicitly set
 - Core: Fix context compaction failing when conversation contains media parts (images, audio, video) — switch from blacklist filtering (exclude `ThinkPart`) to whitelist filtering (only keep `TextPart`) to prevent unsupported content types from being sent to the compaction API
 - Web: Fix `@` file mention index not refreshing after switching sessions or when workspace files change — reset index on session switch, auto-refresh after 30s staleness, and support path-prefix search beyond the 500-file limit
diff --git a/docs/zh/release-notes/changelog.md b/docs/zh/release-notes/changelog.md
index 040492456..586b01995 100644
--- a/docs/zh/release-notes/changelog.md
+++ b/docs/zh/release-notes/changelog.md
@@ -4,6 +4,7 @@
 
 ## 未发布
 
+- Core：修复部分 Linux 系统（如内核版本 6.8.0-101）上 HTTP 请求头包含尾部空白/换行符导致连接错误的问题——发送前对 ASCII 请求头值执行空白裁剪
 - Core：修复 OpenAI Responses provider 隐式发送 `reasoning.effort=null` 导致需要推理的 Responses 兼容端点报错的问题——现在仅在显式设置时才发送推理参数
 - Core：修复对话包含媒体内容（图片、音频、视频）时上下文压缩失败的问题——将过滤策略从黑名单（排除 `ThinkPart`）改为白名单（仅保留 `TextPart`），防止不支持的内容类型被发送到压缩 API
 - Web：修复 `@` 文件提及索引在切换会话或工作区文件变更后不刷新的问题——切换会话时重置索引，30 秒过期自动刷新，输入路径前缀可查找超出 500 文件上限的文件
diff --git a/src/kimi_cli/auth/oauth.py b/src/kimi_cli/auth/oauth.py
index 96d025d96..801fee3e4 100644
--- a/src/kimi_cli/auth/oauth.py
+++ b/src/kimi_cli/auth/oauth.py
@@ -195,7 +195,7 @@ def get_device_id() -> str:
 def _ascii_header_value(value: str, *, fallback: str = "unknown") -> str:
     try:
         value.encode("ascii")
-        return value
+        return value.strip()
     except UnicodeEncodeError:
         sanitized = value.encode("ascii", errors="ignore").decode("ascii").strip()
         return sanitized or fallback
diff --git a/tests/auth/test_ascii_header.py b/tests/auth/test_ascii_header.py
new file mode 100644
index 000000000..0deb1e6c8
--- /dev/null
+++ b/tests/auth/test_ascii_header.py
@@ -0,0 +1,42 @@
+"""Tests for _ascii_header_value and _common_headers in oauth module.
+
+Regression tests for the issue where Linux kernel version strings containing
+trailing whitespace/newlines (e.g. platform.version() returning
+"#101-Ubuntu SMP ...\n") would be included in HTTP headers, causing
+connection errors.
+"""
+
+from unittest.mock import patch
+
+from kimi_cli.auth.oauth import _ascii_header_value, _common_headers
+
+
+class TestAsciiHeaderValue:
+    """Test cases for _ascii_header_value."""
+
+    def test_plain_ascii(self) -> None:
+        assert _ascii_header_value("hello") == "hello"
+
+    def test_strips_trailing_newline(self) -> None:
+        """Regression: Linux platform.version() may contain trailing newline."""
+        assert _ascii_header_value("6.8.0-101\n") == "6.8.0-101"
+
+    def test_non_ascii_sanitized(self) -> None:
+        assert _ascii_header_value("héllo") == "hllo"
+
+    def test_all_non_ascii_returns_fallback(self) -> None:
+        assert _ascii_header_value("你好") == "unknown"
+
+
+class TestCommonHeaders:
+    """Test that _common_headers returns clean header values."""
+
+    @patch("kimi_cli.auth.oauth.platform")
+    @patch("kimi_cli.auth.oauth.get_device_id", return_value="abc123")
+    def test_no_whitespace_in_header_values(self, _mock_device_id, mock_platform) -> None:
+        """All header values must be free of leading/trailing whitespace."""
+        mock_platform.node.return_value = "myhost"
+        mock_platform.version.return_value = "#101-Ubuntu SMP\n"
+        headers = _common_headers()
+        for key, value in headers.items():
+            assert value == value.strip(), f"Header {key!r} has untrimmed whitespace: {value!r}"