Buffer overflow in the thread scheduler in Chicken before 4.8.0.1 allows attackers to cause a denial of service (crash) by opening a file descriptor with a large integer value.

Chicken before 4.8.0 does not properly handle NUL bytes in certain strings, which allows an attacker to conduct "poisoned NUL byte attack."

A casting error in Chicken before 4.8.0 on 64-bit platform caused the random number generator to return a constant value. NOTE: the vendor states "This function wasn't used for security purposes (and is advertised as being unsuitable)."

Chicken before 4.8.0 is susceptible to algorithmic complexity attacks related to hash table collisions.

Untrusted search path vulnerability in csi in Chicken before 4.8.2 allows local users to execute arbitrary code via a Trojan horse .csirc in the current working directory.

OS command injection vulnerability in the "qs" procedure from the "utils" module in Chicken before 4.9.0.

Multiple buffer overflows in the (1) R5RS char-ready, (2) tcp-accept-ready, and (3) file-select procedures in Chicken through 4.8.0.3 allows attackers to cause a denial of service (crash) by opening a file descriptor with a large integer value. NOTE: this issue exists because of an incomplete fix for CVE-2012-6122.

Buffer overflow in the "read-string!" procedure in the "extras" unit in CHICKEN stable before 4.8.0.5 and development snapshots before 4.8.3 allows remote attackers to cause a denial of service (memory corruption and application crash) and possibly execute arbitrary code via a "#f" value in the NUM argument.

Buffer overflow in the "read-u8vector!" procedure in the srfi-4 unit in CHICKEN stable 4.8.0.7 and development snapshots before 4.9.1 allows remote attackers to cause a denial of service (memory corruption and application crash) and possibly execute arbitrary code via a "#f" value in the NUM argument.

Buffer overflow in CHICKEN 4.9.0 and 4.9.0.1 may allow remote attackers to execute arbitrary code via the 'select' function.

Buffer overflow in CHICKEN 4.9.0.x before 4.9.0.2, 4.9.x before 4.9.1, and before 5.0 allows attackers to have unspecified impact via a positive START argument to the "substring-index[-ci] procedures."

The string-translate* procedure in the data-structures unit in CHICKEN before 4.10.0 allows remote attackers to cause a denial of service (crash).

Directory traversal vulnerability in Spiffy before 5.4.

The "spiffy-cgi-handlers" egg would convert a nonexistent "Proxy" header to the HTTP_PROXY environment variable, which would allow attackers to direct CGI programs which use this environment variable to use an attacker-specified HTTP proxy server (also known as a "httpoxy" attack). This affects all versions of spiffy-cgi-handlers before 0.5.

The "http-client" egg always used a HTTP_PROXY environment variable to determine whether HTTP traffic should be routed via a proxy, even when running as a CGI process. Under several web servers this would mean a user-supplied "Proxy" header could allow an attacker to direct all HTTP requests through a proxy (also known as a "httpoxy" attack). This affects all versions of http-client before 0.10.

The "process-execute" and "process-spawn" procedures in CHICKEN Scheme used fixed-size buffers for holding the arguments and environment variables to use in its execve() call. This would allow user-supplied argument/environment variable lists to trigger a buffer overrun. This affects all releases of CHICKEN up to and including 4.11 (it will be fixed in 4.12 and 5.0, which are not yet released).

The "process-execute" and "process-spawn" procedures did not free memory correctly when the execve() call failed, resulting in a memory leak. This could be abused by an attacker to cause resource exhaustion or a denial of service. This affects all releases of CHICKEN up to and including 4.11 (it will be fixed in 4.12 and 5.0, which are not yet released).

Due to an incomplete fix for CVE-2012-6125, all versions of CHICKEN Scheme up to and including 4.12.0 are vulnerable to an algorithmic complexity attack. An attacker can provide crafted input which, when inserted into the symbol table, will result in O(n) lookup time.

An issue was discovered in CHICKEN Scheme through 4.12.0. When using a nonstandard CHICKEN-specific extension to allocate an SRFI-4 vector in unmanaged memory, the vector size would be used in unsanitised form as an argument to malloc(). With an unexpected size, the impact may have been a segfault or buffer overflow.

An incorrect "pair?" check in the Scheme "length" procedure results in an unsafe pointer dereference in all CHICKEN Scheme versions prior to 4.13, which allows an attacker to cause a denial of service by passing an improper list to an application that calls "length" on it.

egg-compile.scm in CHICKEN 5.x before 5.3.1 allows arbitrary OS command execution during package installation via escape characters in a .egg file.