RFC 9851: TLS 1.2 is in Feature Freeze

3 hours ago

TLS 1.3 is replacing TLS 1.2 due to security fixes like encrypted traffic and stronger cryptography.
No further changes will be approved for TLS 1.2 except urgent security fixes, new TLS Exporter Labels, and ALPN Protocol IDs.
Post-quantum cryptography (PQC) for TLS 1.2 will not be specified; users must upgrade to TLS 1.3 for quantum-safe security.
TLS registries remain open but new entries must be intended for TLS 1.3 or later, not TLS 1.2.
The document modifies IANA instructions to restrict TLS 1.2 entries and adds notes to 25 TLS registries.

RFC 10015 deprecates Diffie-Hellman (DH) over finite fields and RSA key exchanges in (D)TLS 1.2, and discourages static Elliptic Curve Diffie-Hellman (ECDH) cipher suites.
Non-ephemeral DH algorithms lack forward secrecy and are vulnerable to attacks like Raccoon (timing side channel) and invalid curve attacks due to key reuse.
Ephemeral FFDHE in (D)TLS 1.2 has interoperability issues, small subgroups, weak 1024-bit groups, and Raccoon vulnerability, with no mechanism for secure fallback.

G1 becomes the default garbage collector in all environments, having been improved to match or exceed the performance of Serial GC.
Post-quantum hybrid key exchange for TLS 1.3 is introduced to enhance security against future quantum computing threats.
Compact object headers are enabled by default, reducing memory usage and improving performance.

Mastodon serves different content (HTML, ActivityPub JSON, API JSON) for the same URL based on the Accept header, requiring careful cache key normalization.
The cache key must include a normalized variant of the Accept header to prevent serving the wrong content type to clients.
Key assumptions: AUTHORIZED_FETCH disabled, no signed URLs, federation uses HTTP Signatures (not Authorization header).

The 2026-07-28 Model Context Protocol (MCP) specification introduces a stateless protocol core, transforming MCP from a bidirectional stateful protocol into a request/response stateless one for improved reliability and scalability.
Every request is self-describing with optional discovery; methods and tool names travel in HTTP headers for routing and authorization.
Multi Round-Trip Requests (MRTR) replace server-initiated bidirectional streams, enabling stateless interactions like user input requests mid-call.

A CDN caching bug on RubyGems.org potentially exposed one user's legacy API key to another for up to an hour, affecting clients older than v3.2.0 (specifically using GET /api/v1/api_key with gzip compression).
The bug resulted from a specific interaction between response compression and cache headers, allowing cached responses at Fastly edge nodes to serve incorrect keys without re-authenticating.
All legacy API keys have been revoked as a precaution, and users are urged to check their gems for unauthorized versions, yanks, owners, or webhooks.

RFC 10015 deprecates Diffie-Hellman (DH) over finite fields and RSA key exchanges in (D)TLS 1.2, and discourages static Elliptic Curve Diffie-Hellman (ECDH) cipher suites.
Non-ephemeral DH algorithms lack forward secrecy and are vulnerable to attacks like Raccoon (timing side channel) and invalid curve attacks due to key reuse.
Ephemeral FFDHE in (D)TLS 1.2 has interoperability issues, small subgroups, weak 1024-bit groups, and Raccoon vulnerability, with no mechanism for secure fallback.

G1 becomes the default garbage collector in all environments, having been improved to match or exceed the performance of Serial GC.
Post-quantum hybrid key exchange for TLS 1.3 is introduced to enhance security against future quantum computing threats.
Compact object headers are enabled by default, reducing memory usage and improving performance.

Mastodon serves different content (HTML, ActivityPub JSON, API JSON) for the same URL based on the Accept header, requiring careful cache key normalization.
The cache key must include a normalized variant of the Accept header to prevent serving the wrong content type to clients.
Key assumptions: AUTHORIZED_FETCH disabled, no signed URLs, federation uses HTTP Signatures (not Authorization header).

The 2026-07-28 Model Context Protocol (MCP) specification introduces a stateless protocol core, transforming MCP from a bidirectional stateful protocol into a request/response stateless one for improved reliability and scalability.
Every request is self-describing with optional discovery; methods and tool names travel in HTTP headers for routing and authorization.
Multi Round-Trip Requests (MRTR) replace server-initiated bidirectional streams, enabling stateless interactions like user input requests mid-call.

A CDN caching bug on RubyGems.org potentially exposed one user's legacy API key to another for up to an hour, affecting clients older than v3.2.0 (specifically using GET /api/v1/api_key with gzip compression).
The bug resulted from a specific interaction between response compression and cache headers, allowing cached responses at Fastly edge nodes to serve incorrect keys without re-authenticating.
All legacy API keys have been revoked as a precaution, and users are urged to check their gems for unauthorized versions, yanks, owners, or webhooks.

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