Please do not open a public issue. Use GitHub's private vulnerability reporting for this repository. You should get a response within a few days. Once a fix is released you will be credited in the advisory unless you prefer otherwise.

Security fixes go into the latest release.

Release archives and packages are covered by checksums.txt, which the release workflow signs keylessly with cosign using its GitHub OIDC identity. No signing keys exist to leak.

VERSION=0.2.0
REL=https://github.com/rossedman/postmarkd/releases/download/v$VERSION
curl -fsSLO $REL/checksums.txt
curl -fsSLO $REL/checksums.txt.sigstore.json
cosign verify-blob \
  --bundle checksums.txt.sigstore.json \
  --certificate-identity-regexp '^https://github\.com/rossedman/postmarkd/\.github/workflows/release\.yml@refs/tags/v' \
  --certificate-oidc-issuer https://token.actions.githubusercontent.com \
  checksums.txt
sha256sum --ignore-missing -c checksums.txt

Container images on ghcr.io/rossedman/postmarkd are signed the same way (cosign verify with the same identity flags), and archives, packages and images carry build provenance attestations (gh attestation verify <file or oci://image> --repo rossedman/postmarkd). Releases up to v0.1.0 were published before signing was added.

• postmarkd can send mail as your domain. Treat access to its socket or port like access to your Postmark server token.
• Keep the default unix socket, or enable POSTMARKD_AUTH_TOKENS and put TLS in front of postmarkd before exposing it on a network.
• Load the Postmark token with a systemd credential rather than the config file or environment (see docs/configuration.md).