Red Hat Security Advisory: python-tornado security update
🔗 CVE IDs covered (1)
📋 Description
CVE-2026-103262 — tornado: Tornado: Denial of Service via decompression bomb in CurlAsyncHTTPClient
🎯 Affected products14
- Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python-tornado-0:6.5.10-0.el10_0.1.src as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python-tornado-debugsource-0:6.5.10-0.el10_0.1.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python-tornado-debugsource-0:6.5.10-0.el10_0.1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python-tornado-debugsource-0:6.5.10-0.el10_0.1.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python-tornado-debugsource-0:6.5.10-0.el10_0.1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-0:6.5.10-0.el10_0.1.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-0:6.5.10-0.el10_0.1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-0:6.5.10-0.el10_0.1.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-0:6.5.10-0.el10_0.1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-debuginfo-0:6.5.10-0.el10_0.1.aarch64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-debuginfo-0:6.5.10-0.el10_0.1.ppc64le as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-debuginfo-0:6.5.10-0.el10_0.1.s390x as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
- python3-tornado-debuginfo-0:6.5.10-0.el10_0.1.x86_64 as a component of Red Hat Enterprise Linux AppStream EUS (v. 10.0)
✅ Remediation
For details on how to apply this update, which includes the changes described in this advisory, refer to: https://access.redhat.com/articles/11258 Workaround: Restrict outbound HTTP client requests to trusted destinations and avoid using the CurlAsyncHTTPClient backend when fetching untrusted web content. 1. Application configuration: Configure Tornado applications to utilize the default SimpleAsyncHTTPClient instead of CurlAsyncHTTPClient, provided specialized libcurl functionality (such as custom proxy configurations or specific TLS options) is not required. The default client enforces strict size boundaries on compressed and uncompressed response bodies. 2. Network egress filtering: Implement firewall rules or egress network policies to restrict outbound HTTP/HTTPS connections exclusively to verified, trustworthy endpoints, preventing the client from contacting potentially malicious third-party servers. 3. Operational controls: Ensure that user-supplied or untrusted URLs are validated, sanitized, or rejected before initiating outbound retrieval requests. Caveats: Switching the HTTP client backend from CurlAsyncHTTPClient to SimpleAsyncHTTPClient may disrupt services that depend on libcurl-specific features. Enforcing egress filtering may block connections to unlisted external services.