SSL/TLS Test Lab: 20 broken and modern HTTPS test sites

A Let's Encrypt 6-day certificate (shortlived profile) that was issued once and never renewed, so it expired 160 hours after issuance.

Chrome and Edge show NET::ERR_CERT_DATE_INVALID; Firefox shows SEC_ERROR_EXPIRED_CERTIFICATE; Safari says the connection is not private.

Fails with the expired finding: notAfter is in the past and days_left is negative.

A self-signed certificate generated by sslsh testlab gen: the issuer is the certificate itself, no CA involved.

Chrome and Edge show NET::ERR_CERT_AUTHORITY_INVALID; Firefox shows MOZILLA_PKIX_ERROR_SELF_SIGNED_CERT.

Fails with self_signed (the chain is not trusted). Plain curl reports curl: (60) SSL certificate problem: self-signed certificate.

Leaf → intermediate → a private root (“ssl.sh Test Lab Untrusted Root”) that is in no trust store and is never published. The server sends the leaf and the intermediate.

Chrome and Edge show NET::ERR_CERT_AUTHORITY_INVALID; Firefox shows SEC_ERROR_UNKNOWN_ISSUER.

Fails with untrusted_root. Plain curl reports curl: (60) SSL certificate problem: self-signed certificate in certificate chain or unable to get local issuer certificate.

Serves ssl.sh's own valid Let's Encrypt certificate, which only covers ssl.sh and www.ssl.sh, not wrong-host.test.ssl.sh.

Chrome and Edge show NET::ERR_CERT_COMMON_NAME_INVALID; Firefox shows SSL_ERROR_BAD_CERT_DOMAIN.

Fails with hostname_mismatch; the SAN list shows ssl.sh and www.ssl.sh. Plain curl reports no alternative certificate subject name matches target host name.

A valid Let's Encrypt certificate, but the server sends only the leaf (cert.pem instead of fullchain.pem), so the intermediate is missing.

Usually loads: Chrome, Edge and Safari fetch the missing intermediate through the AIA URL, and Firefox ships known intermediates. Older Android devices, apps and command-line tools fail.

Fails with incomplete_chain. curl, OpenSSL, Python and Node.js report unable to get local issuer certificate.

A Let's Encrypt 90-day certificate (classic profile, which carries a CRL URL) revoked right after issuance with reason keyCompromise. It is re-issued and revoked about every 80 days.

Firefox (CRLite) shows SEC_ERROR_REVOKED_CERTIFICATE. Chrome and Edge show NET::ERR_CERT_REVOKED only once the serial reaches Chrome's CRLSet; until then the page loads. Safari depends on Apple's revocation service.

Reports revoked when the checker consults the CA's CRL. Plain curl and OpenSSL don't check revocation and connect normally.

A certificate from the lab CA whose Extended Key Usage contains both serverAuth and clientAuth: the multi-purpose combination publicly trusted CAs phased out in 2025–2026.

Without the lab root: NET::ERR_CERT_AUTHORITY_INVALID / SEC_ERROR_UNKNOWN_ISSUER. With the name-constrained lab root imported it loads: browsers don't reject the extra clientAuth EKU.

Shows the client_auth_eku finding (a public CA won't renew this certificate with the same EKUs) plus untrusted_root.

Only TLS 1.0 is enabled (ssl_protocols TLSv1 with @SECLEVEL=0, because OpenSSL 3 refuses TLS 1.0 at its default security level).

Every current browser refuses: Chrome and Edge show ERR_SSL_VERSION_OR_CIPHER_MISMATCH, Firefox shows SSL_ERROR_UNSUPPORTED_VERSION.

The quick check fails with tls_handshake_failed; a full check should list TLS 1.0 as the only enabled protocol.

Only TLS 1.1 is enabled (ssl_protocols TLSv1.1 with @SECLEVEL=0).

Same as TLS 1.0: ERR_SSL_VERSION_OR_CIPHER_MISMATCH in Chrome and Edge, SSL_ERROR_UNSUPPORTED_VERSION in Firefox.

The quick check fails with tls_handshake_failed; a full check should list TLS 1.1 as the only enabled protocol.

Only TLS 1.2 is enabled (ssl_protocols TLSv1.2).

Loads normally in every current browser, negotiated as TLS 1.2.

Passes with tls_version TLSv1.2; a full check notes that TLS 1.3 is not offered (informational, not an error).

Only TLS 1.3 is enabled (ssl_protocols TLSv1.3).

Loads in every current browser. Clients limited to TLS 1.2 (Android 9 and older, Windows 10's built-in TLS stack, old Java 8 builds) fail with a protocol error.

Passes with tls_version TLSv1.3; a full check shows TLS 1.2 disabled.

TLS 1.3 only, and the only key-exchange group is the post-quantum hybrid X25519MLKEM768 (ssl_ecdh_curve X25519MLKEM768; nginx must be linked against OpenSSL 3.5 or newer).

Recent Chrome, Edge, Firefox and Safari 26 connect because they send an X25519MLKEM768 key share by default. Older browsers and most HTTP libraries fail the handshake (Chrome: ERR_SSL_VERSION_OR_CIPHER_MISMATCH).

Passes with key_exchange_group X25519MLKEM768 when the checker's OpenSSL is 3.5+; with an older OpenSSL it fails with tls_handshake_failed.

Valid certificate plus Strict-Transport-Security: max-age=31536000; includeSubDomains.

Loads normally. After the first visit the browser rewrites http:// to https:// on its own (Chrome DevTools shows a “307 Internal Redirect”), and certificate errors on this host can no longer be clicked through.

Passes; a full check reports HSTS with max-age 31536000.

Valid certificate, no HSTS header; plain HTTP is redirected to HTTPS with a 301 only.

Loads normally and looks fine. The weakness is invisible: every first request over plain HTTP can be intercepted (SSL stripping).

Passes the certificate checks; a full check adds the no_hsts finding.

An HTTPS page that loads an image and a script over plain http://.

Chrome and Edge block the script and upgrade the image to HTTPS; the DevTools console shows “Mixed Content” messages. Firefox also blocks the script. The page itself tells you whether the HTTP script ran.

Passes: the TLS setup is fine. Mixed content is a page problem, not a certificate problem; scan the page instead.

A lab-CA certificate valid for 3,650 days. Publicly trusted certificates have been capped at 200 days since 15 March 2026 (CA/Browser Forum ballot SC-081), falling to 47 days in 2029.

Without the lab root: NET::ERR_CERT_AUTHORITY_INVALID. With the lab root imported, Chrome and Firefox load it (lifetime caps only apply to public roots), while Safari and other Apple clients reject TLS certificates valid longer than 825 days even from user-installed roots.

Fails with untrusted_root; validity_days is 3650, far above the 200-day public maximum.

A Let's Encrypt shortlived certificate: valid for 160 hours (about 6.7 days) and renewed automatically every 2–3 days.

Loads normally.

Passes; validity_days is 7 (160 hours rounded up) and days_left is between 0 and 6. A short remaining lifetime is expected here, not a renewal failure.

A Let's Encrypt certificate with an ECDSA P-256 key.

Loads normally.

Passes; key_type is “ECDSA P-256”.

A Let's Encrypt certificate with a 4096-bit RSA key.

Loads normally; the handshake costs the server more CPU than ECDSA P-256 but the difference is not visible to visitors.

Passes; key_type is “RSA 4096”.

The server requires a client certificate issued by the lab client CA (ssl_verify_client on). A test client certificate is published at test.ssl.sh/downloads/.

Without a client certificate nginx answers “400 Bad Request — No required SSL certificate was sent”. Import client.p12 (password ssl.sh) and the browser asks you to pick it; the page then loads.

The server certificate passes. An HTTP request without a client certificate gets 400; curl --cert client.pem --key client.key https://mtls-required.test.ssl.sh/ gets 200.