kern 1.2.0
Egress control, descriptor ownership, security hardening
Release notes
Strict egress mode
KERN_NET_POLICY=strict with a KERN_NET_ALLOW list means deny-all by default. Every dial, DNS lookup and UDP send to an unlisted destination is refused with a SIEM event. Becomes the default in 1.3.0.
Descriptor ownership (A38)
Every API that hands out a file descriptor now hands out a handle that names the open it came from. A close wakes blocked operations and the last one to finish performs the close; a handle used after close fails even once the number is reused. Eliminates the class of bug where closing a descriptor on one thread lets another thread's I/O land on a different connection.
Protocol-client ownership (A46)
MQTT, gRPC, NATS, SSH and WebSocket clients are now owned records. A close wakes a call blocked on the connection; a call on a closed value fails cleanly.
Shared list safety (A35)
Slot stores are now release-ordered, reader loads acquire, writers take the container lock, and sorts/shuffle/clear are locked.
Cap<Recon>
Port probes and banner grabs need their own capability; Cap<Net> for scanning is deprecated (W0004, E0422 under edition 2027).
UDP/NTP/mDNS/libpq egress
Now go through the allowlist and the SSRF screen; cloud metadata and link-local addresses are refused at default SSRF level.
KERN_NET_ALLOW hardened
No more truncation at 1024 bytes, no port misparse, malformed list refuses all traffic.
macOS VM proxy fix
A guest could redirect published-port traffic to another VM on the same host.
Async fixes
Async file/DNS calls inside routines returned wrong results; multiple multi-worker correctness fixes.
Cloud plane
Rescue mode (UR-102), power_cycle, per-instance events, cloud-init user_data for VMs (UR-108), volume resize in place (UR-110), container hostname best-effort (UR-109).
HTTP client deadline
Total deadline across connect, TLS, writes, reads, redirects and retries (default 120s).
Fuzz
Python parser fuzzers ported to Kern-native.
By the numbers
2,241 tests (1,669 conformance + 85 compat + 487 negative). 435 stdlib modules (310 core + 125 in 10 packages), 4,878 pub fns. 62K-line compiler, 74K C runtime (46,006-line audited TCB). 14 fuzz targets (8 C libFuzzer + 6 Kern-language).