TLS Certificate
E5
About E5
- Operator
- Internet Security Research Group (ISRG)
- Chains to
- ISRG Root X2
- Key type
- ECDSA
- In use since
- 2024
ECDSA DV TLS via ACME for clients that prefer elliptic-curve chains (smaller handshake, faster).
Chains to the newer ECDSA root X2 rather than X1.
Frequently asked questions
Is E5 a legitimate certificate authority?
Yes. E5 is a publicly trusted intermediate CA operated by Internet Security Research Group (ISRG) and chained to ISRG Root X2. It is recognized by all mainstream browsers and operating system trust stores. The certificate itself is not a phishing indicator — the same intermediate signs millions of legitimate sites.
Why does E5 show up on phishing sites?
Internet Security Research Group (ISRG) issues ECDSA domain-validated certificates automatically and at no cost (or very low cost), which is the exact workflow scammers need to put HTTPS on a throwaway domain. Domain validation only proves that the requester controls the domain name, not that the site behind it is trustworthy. phishunt lists the specific domains currently flagged below — those are the suspicious ones, not E5 itself.
How do I verify a certificate issued by E5?
In a desktop browser, click the padlock in the address bar and open the certificate viewer. Confirm the issuer chain ends at ISRG Root X2, that the subject matches the domain you expect, and that the notAfter date has not passed. A valid E5 certificate only proves TLS was negotiated correctly — always verify the domain name itself belongs to the service you intended to visit.
What is the difference between E5 and E6?
E5 and its siblings (E6, E7, E8, R10) share the same operator (Internet Security Research Group (ISRG)) and roll up to the same root (ISRG Root X2). CAs rotate multiple intermediates so that if one key ever has to be revoked, the damage is contained. As a user, you can treat all of them as the same trust anchor.
It is strongly recommended to use them for Threat Hunting or add them to a Watchlist.
| Last check (UTC) | First seen (UTC) ▾ | URL | Screenshot | Flags | Details |
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It is strongly recommended to use them for Threat Hunting or add them to a Watchlist.
| URL | Screenshot | Flags | Details |
|---|