A flaw was found in libssh username handling for ProxyCommand expansion. The sshcheckusernamesyntax() validation path in src/misc.c used an incomplete dangerous-character filter for usernames expanded through %r. As a result, specially crafted usernames containing shell-significant characters could reach shell-evaluated ProxyCommand handling and influence shell expansion, exposing environment variables and causing unintended shell behavior. This issue affects clients that combine untrusted username input with ProxyCommand-style shell execution.
A flaw was found in OpenSSH. This vulnerability, a heap out-of-bounds read, occurs during the cleanup of GSSAPI (Generic Security Service Application Programming Interface) indicators when a trailing NULL termination is missing in the auth-indicators array. A remote attacker, under specific configurations involving GSSAPI authentication and a Kerberos environment, could exploit this to cause the SSH authentication path to crash or abort. This leads to a denial of service (DoS), impacting the availability of the SSH service.
A flaw was identified in the RelaxNG parser of libxml2 related to how external schema inclusions are handled. The parser does not enforce a limit on inclusion depth when resolving nested <include> directives. Specially crafted or overly complex schemas can cause excessive recursion during parsing. This may lead to stack exhaustion and application crashes, creating a denial-of-service risk.
A flaw was found in gnutls. A remote attacker could exploit this vulnerability by presenting a specially crafted Online Certificate Status Protocol (OCSP) response during a TLS handshake. Due to a logic error in how gnutls processes multi-record OCSP responses, a client with OCSP verification enabled may incorrectly accept a revoked server certificate, potentially leading to a compromise of trust.
A flaw was found in the libxml2 library. This uncontrolled resource consumption vulnerability occurs when processing XML catalogs that contain repeated <nextCatalog> elements pointing to the same downstream catalog. A remote attacker can exploit this by supplying crafted catalogs, causing the parser to redundantly traverse catalog chains. This leads to excessive CPU consumption and degrades application availability, resulting in a denial-of-service condition.