ALAS2-2026-3847

References: CVE-2026-49853  CVE-2026-49854  CVE-2026-49855 
FAQs regarding Amazon Linux ALAS/CVE Severity

Issue Overview:

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, SimpleAsyncHTTPClient shallow-copied redirected requests and removed only the Host header, leaving Authorization, auth_username, auth_password, and auth_mode in place when a redirect changed scheme, host, or port. This issue is fixed in version 6.5.6. (CVE-2026-49853)

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, the optional native extension tornado.speedups implemented websocket_mask without validating that the mask argument is exactly four bytes, allowing the C function to read up to three bytes beyond the provided buffer when reached through Tornado XSRF token decoding with the native extension active. This issue is fixed in version 6.5.6. (CVE-2026-49854)

Tornado is a Python web framework and asynchronous networking library. Prior to 6.5.6, Tornado gzip decompression routines processed limited-size chunks but did not enforce an overall limit on accumulated decompressed chunks, allowing a malicious server accessed by SimpleAsyncHTTPClient or an HTTPServer configured with decompress_request=True to consume effectively unlimited memory. This issue is fixed in version 6.5.6. (CVE-2026-49855)

Issue Correction:
Run yum update python-tornado or yum update --advisory ALAS2-2026-3847 to update your system.

New Packages:

aarch64:
    python-tornado-4.2.1-3.amzn2.0.6.aarch64
    python-tornado-doc-4.2.1-3.amzn2.0.6.aarch64
    python-tornado-debuginfo-4.2.1-3.amzn2.0.6.aarch64

i686:
    python-tornado-4.2.1-3.amzn2.0.6.i686
    python-tornado-doc-4.2.1-3.amzn2.0.6.i686
    python-tornado-debuginfo-4.2.1-3.amzn2.0.6.i686

src:
    python-tornado-4.2.1-3.amzn2.0.6.src

x86_64:
    python-tornado-4.2.1-3.amzn2.0.6.x86_64
    python-tornado-doc-4.2.1-3.amzn2.0.6.x86_64
    python-tornado-debuginfo-4.2.1-3.amzn2.0.6.x86_64