An exploitable SQL injection vulnerability exists in the administrator web portal function of coTURN prior to version 4.5.0.9. A login message with a specially crafted username can cause an SQL injection, resulting in authentication bypass, which could give access to the TURN server administrator web portal. An attacker can log in via the external interface of the TURN server to trigger this vulnerability.

An exploitable unsafe default configuration vulnerability exists in the TURN server functionality of coTURN prior to 4.5.0.9. By default, the TURN server allows relaying external traffic to the loopback interface of its own host. This can provide access to other private services running on that host, which can lead to further attacks. An attacker can set up a relay with a loopback address as the peer on an affected TURN server to trigger this vulnerability.

An exploitable unsafe default configuration vulnerability exists in the TURN server function of coTURN prior to version 4.5.0.9. By default, the TURN server runs an unauthenticated telnet admin portal on the loopback interface. This can provide administrator access to the TURN server configuration, which can lead to additional attacks. An attacker who can get access to the telnet port can gain administrator access to the TURN server.

Coturn is free open source implementation of TURN and STUN Server. Coturn before version 4.5.2 by default does not allow peers to connect and relay packets to loopback addresses in the range of `127.x.x.x`. However, it was observed that when sending a `CONNECT` request with the `XOR-PEER-ADDRESS` value of `0.0.0.0`, a successful response was received and subsequently, `CONNECTIONBIND` also received a successful response. Coturn then is able to relay packets to the loopback interface. Additionally, when coturn is listening on IPv6, which is default, the loopback interface can also be reached by making use of either `[::1]` or `[::]` as the peer address. By using the address `0.0.0.0` as the peer address, a malicious user will be able to relay packets to the loopback interface, unless `--denied-peer-ip=0.0.0.0` (or similar) has been specified. Since the default configuration implies that loopback peers are not allowed, coturn administrators may choose to not set the `denied-peer-ip` setting. The issue patched in version 4.5.2. As a workaround the addresses in the address block `0.0.0.0/8`, `[::1]` and `[::]` should be denied by default unless `--allow-loopback-peers` has been specified.

In coturn before version 4.5.1.3, there is an issue whereby STUN/TURN response buffer is not initialized properly. There is a leak of information between different client connections. One client (an attacker) could use their connection to intelligently query coturn to get interesting bytes in the padding bytes from the connection of another client. This has been fixed in 4.5.1.3.

An exploitable heap out-of-bounds read vulnerability exists in the way CoTURN 4.5.1.1 web server parses POST requests. A specially crafted HTTP POST request can lead to information leaks and other misbehavior. An attacker needs to send an HTTPS request to trigger this vulnerability.

An exploitable denial-of-service vulnerability exists in the way CoTURN 4.5.1.1 web server parses POST requests. A specially crafted HTTP POST request can lead to server crash and denial of service. An attacker needs to send an HTTP request to trigger this vulnerability.

Coturn is a free open source implementation of TURN and STUN Server. Coturn is commonly configured to block loopback and internal ranges using "denied-peer-ip" and/or default loopback restrictions. CVE-2020-26262 addressed bypasses involving "0.0.0.0", "[::1]" and "[::]", but IPv4-mapped IPv6 is not covered. When sending a "CreatePermission" or "ChannelBind" request with the "XOR-PEER-ADDRESS" value of "::ffff:127.0.0.1", a successful response is received, even though "127.0.0.0/8" is blocked via "denied-peer-ip". The root cause is that, prior to the updated fix implemented in version 4.9.0, three functions in "src/client/ns_turn_ioaddr.c" do not check "IN6_IS_ADDR_V4MAPPED". "ioa_addr_is_loopback()" checks "127.x.x.x" (AF_INET) and "::1" (AF_INET6), but not "::ffff:127.0.0.1." "ioa_addr_is_zero()" checks "0.0.0.0" and "::", but not "::ffff:0.0.0.0." "addr_less_eq()" used by "ioa_addr_in_range()" for "denied-peer-ip" matching: when the range is AF_INET and the peer is AF_INET6, the comparison returns 0 without extracting the embedded IPv4. Version 4.9.0 contains an updated fix to address the bypass of the fix for CVE-2020-26262.

Coturn is a free open source implementation of TURN and STUN Server. Prior to 4.10.0, the STUN/TURN attribute parsing functions in coturn perform unsafe pointer casts from uint8_t * to uint16_t * without alignment checks. When processing a crafted STUN message with odd-aligned attribute boundaries, this results in misaligned memory reads at ns_turn_msg.c. On ARM64 architectures (AArch64) with strict alignment enforcement, this causes a SIGBUS signal that immediately kills the turnserver process. An unauthenticated remote attacker can crash any ARM64 coturn deployment by sending a single crafted UDP packet. This vulnerability is fixed in 4.10.0.