mkj Dropbear S Range Check curve25519.c unpackneg signature verification
A vulnerability was determined in mkj Dropbear up to 2025.89. Impacted is the function unpackneg of the file src/curve25519.c of the component S Range Check. This manipulation causes improper verification of cryptographic signature. The attack can be initiated remotely. The attack is considered to have high complexity. The exploitability is considered difficult. The actual existence of this vulnerability is currently in question. Patch name: fdec3c90a15447bd538641d85e5a3e3ac981011d. To fix this issue, it is recommended to deploy a patch. The project maintainer explains: "Signature Malleability is not exploitable in SSH protocol. (...) [A] PoC
Dropbear: privilege escalation via unix domain socket forwardings
A flaw was found in Dropbear. When running in multi-user mode and authenticating users, the dropbear ssh server does the socket forwardings requested by the remote client as root,
only switching to the logged-in user upon spawning a shell or performing
some operations like reading the user's files.
With the recent ability of also using unix domain sockets as the forwarding destination any user able to log in via ssh can connect to any unix socket with the root's credentials, bypassing both file system restrictions and any SO_PEERCRED / SO_PASSCRED checks performed by the peer.
The SSH transport protocol with certain OpenSSH extensions, found in OpenSSH before 9.6 and other products, allows remote attackers to bypass integrity checks such that some packets are omitted (from the extension negotiation message), and a client and server may consequently end up with a connection for which some security features have been downgraded or disabled, aka a Terrapin attack. This occurs because the SSH Binary Packet Protocol (BPP), implemented by these extensions, mishandles the handshake phase and mishandles use of sequence numbers. For example, there is an effective attack against SSH's use of ChaCha20-Poly1305 (and CBC with E