# TLS_NULL_WITH_NULL_NULL cipher suite

> TLS_NULL_WITH_NULL_NULL (0x00,0x00): NULL/NULL · NULL · SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2. ssl.sh rating: Insecure. OpenSSL/GnuTLS names and Nginx/Apache config.

Source: https://ssl.sh/ciphers/tls-null-with-null-null/
Last updated: 2026-11-10

TLS_NULL_WITH_NULL_NULL (0x00,0x00) is a cipher suite for SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2: NULL key exchange, NULL authentication, NULL encryption and NULL message authentication. ssl.sh rates it Insecure.

| Field | Value |
|---|---|
| IANA | TLS_NULL_WITH_NULL_NULL |
| Hex code | 0x00,0x00 |
| OpenSSL | Not available in OpenSSL 3.5 |
| GnuTLS | - |
| Key exchange | NULL |
| Authentication | NULL |
| Encryption | NULL |
| MAC | NULL |
| TLS versions | SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2 |
| Rating | Insecure |
| IANA "Recommended" | N |
| References | RFC 5246 |

## What each component means

A [cipher suite](https://ssl.sh/glossary/cipher-suite/) names the algorithms a client and server agree on in one handshake. TLS_NULL_WITH_NULL_NULL combines no key exchange, no encryption and no MAC. Each part is explained below with its known weaknesses; for the bigger picture see [how cipher suites work](https://ssl.sh/learn/cipher-suites/).

TLS_NULL_WITH_NULL_NULL is not a usable suite: it describes a connection before its first handshake completes, with no key exchange, no encryption and no MAC. [RFC 5246](https://www.rfc-editor.org/rfc/rfc5246) (2008) says it MUST NOT be negotiated because it gives no more protection than an unsecured connection.

## Why this rating

- No encryption (NULL cipher): traffic is sent in clear text.

## Which TLS libraries support it

Support for TLS_NULL_WITH_NULL_NULL as read from each library's own source code or official documentation on 2026-11-10. “Enabled by default” means the library negotiates it with no configuration; “off by default” means it is implemented but has to be switched on.

| Library | Status | Details |
|---|---|---|
| OpenSSL 3.5 | Not supported | - |
| GnuTLS | Not supported | - |
| BoringSSL | Not supported | - |
| Go crypto/tls | Not supported | - |
| NSS 3.133 | Not supported | - |
| Firefox | Not supported | - |
| Java 21 (SunJSSE) | Not supported | - |
| Windows Schannel (Windows 11 / Server 2022) | Not supported | - |
| rustls 0.23.46 | Not supported | - |

None of the 9 libraries tracked here enables it by default. None of them implements it.

NSS shows the library's own defaults; Firefox switches every NSS suite off at start-up and re-enables only those with a security.ssl3.* or security.tls13.* preference. Java defaults are derived from the jdk.tls.disabledAlgorithms value Oracle documents for JDK 21, which later updates may extend. The OpenSSL and GnuTLS rows only show whether the suite is implemented.

- [BoringSSL — ssl/ssl_cipher.cc (main)](https://boringssl.googlesource.com/boringssl/+/refs/heads/main/ssl/ssl_cipher.cc) (2026-11-10)
- [Go — src/crypto/tls/cipher_suites.go (master)](https://github.com/golang/go/blob/master/src/crypto/tls/cipher_suites.go) (2026-11-10)
- [Go — src/crypto/tls/defaults.go (master)](https://github.com/golang/go/blob/master/src/crypto/tls/defaults.go) (2026-11-10)
- [NSS — lib/ssl/ssl3con.c (as vendored in Firefox)](https://github.com/mozilla-firefox/firefox/blob/main/security/nss/lib/ssl/ssl3con.c) (2026-11-10)
- [NSS — TAG-INFO](https://github.com/mozilla-firefox/firefox/blob/main/security/nss/TAG-INFO) (2026-11-10)
- [Firefox — security/manager/ssl/nsNSSComponent.cpp](https://github.com/mozilla-firefox/firefox/blob/main/security/manager/ssl/nsNSSComponent.cpp) (2026-11-10)
- [Firefox — modules/libpref/init/StaticPrefList.yaml](https://github.com/mozilla-firefox/firefox/blob/main/modules/libpref/init/StaticPrefList.yaml) (2026-11-10)
- [Oracle — JDK 21 Providers Documentation: SunJSSE Cipher Suites](https://docs.oracle.com/en/java/javase/21/security/oracle-providers.html#GUID-7093246A-31A3-4304-AC5F-5FB6400405E2) (2026-11-10)
- [Oracle — JDK 21 JSSE Reference Guide: jdk.tls.disabledAlgorithms](https://docs.oracle.com/en/java/javase/21/security/java-secure-socket-extension-jsse-reference-guide.html) (2026-11-10)
- [Microsoft Learn — TLS Cipher Suites in Windows 11](https://learn.microsoft.com/en-us/windows/win32/secauthn/tls-cipher-suites-in-windows-11) (2026-11-10)
- [Microsoft Learn — TLS Cipher Suites in Windows Server 2022](https://learn.microsoft.com/en-us/windows/win32/secauthn/tls-cipher-suites-in-windows-server-2022) (2026-11-10)
- [docs.rs — rustls 0.23.46 crypto::aws_lc_rs (default provider)](https://docs.rs/rustls/0.23.46/src/rustls/crypto/aws_lc_rs/mod.rs.html) (2026-11-10)

## History and standards status

TLS_NULL_WITH_NULL_NULL (0x00,0x00) is registered in the IANA TLS Cipher Suites registry with [RFC 5246](https://www.rfc-editor.org/rfc/rfc5246), “The Transport Layer Security (TLS) Protocol Version 1.2” (August 2008, Standards Track) as its specification. RFC 5246 has since been obsoleted by [RFC 8446](https://www.rfc-editor.org/rfc/rfc8446) (2018) and [RFC 9846](https://www.rfc-editor.org/rfc/rfc9846) (2026). [RFC 9325](https://www.rfc-editor.org/rfc/rfc9325) (2022), part of BCP 195, says implementations MUST NOT negotiate suites with NULL encryption. The registry marks it N, which per [RFC 8447](https://www.rfc-editor.org/rfc/rfc8447) (2018) means it either hasn't been through the IETF consensus process, has limited applicability or is meant only for specific use cases, not necessarily that it is flawed.

## How to test whether a server accepts it

OpenSSL 3.5 cannot offer TLS_NULL_WITH_NULL_NULL, so openssl s_client can't test it directly; use a scanner that implements the suite itself.

To decode a name or hex code, use the [cipher suite lookup](https://ssl.sh/tools/cipher-suite-lookup/); the [SSL checker](https://ssl.sh/tools/ssl-checker/) shows which protocol versions a live server accepts and the cipher suite it negotiates.

## FAQ

### Is TLS_NULL_WITH_NULL_NULL secure?

No. ssl.sh rates it insecure. No encryption (NULL cipher): traffic is sent in clear text. [RFC 9325](https://www.rfc-editor.org/rfc/rfc9325) (2022), part of BCP 195, says implementations MUST NOT negotiate suites with NULL encryption.

### Can TLS_NULL_WITH_NULL_NULL be used with TLS 1.3?

No. TLS 1.3 has its own suites that name only the AEAD and the hash, and TLS 1.2 suites can't be used in a TLS 1.3 handshake. TLS_NULL_WITH_NULL_NULL works with SSL 3.0, TLS 1.0, TLS 1.1, TLS 1.2. The closest TLS 1.3 suite is [TLS_AES_128_GCM_SHA256](https://ssl.sh/ciphers/tls-aes-128-gcm-sha256/), which TLS 1.3 combines with a separately negotiated key exchange such as X25519.

### How do I disable TLS_NULL_WITH_NULL_NULL in Nginx or Apache?

There is nothing to disable: OpenSSL 3.5, which Nginx and Apache httpd normally use, does not implement TLS_NULL_WITH_NULL_NULL, so they cannot negotiate it.

### Which clients and libraries still support TLS_NULL_WITH_NULL_NULL?

Not supported: OpenSSL 3.5, GnuTLS, BoringSSL, Go crypto/tls, NSS 3.133, Firefox, Java 21 (SunJSSE), Windows Schannel (Windows 11 / Server 2022) and rustls 0.23.46.