LibVNC/libvncserver

LibVNCClient is a library for easy implementation of a VNC client. In 0.9.15 and earlier, LibVNCClient's Tight encoding decoder uses fixed-size 2048-pixel scratch buffers for the Gradient filter, but it does not reject Tight rectangles whose width is larger than 2048 pixels. A malicious VNC server can send a crafted FramebufferUpdate rectangle using Tight encoding with NoZlib | ExplicitFilter and the Gradient filter. When a LibVNCClient-based client connects, the client processes the server-controlled rectangle width and writes beyond fixed-size Gradient buffers. This vulnerability is fixed with commit 5b270544b85233668b98161323297d418a8f5fd1.

LibVNCServer versions 0.9.15 and prior (fixed in commit dc78dee) contain null pointer dereference vulnerabilities in the HTTP proxy handlers within httpProcessInput() in httpd.c that allow remote attackers to cause a denial of service by sending specially crafted HTTP requests. Attackers can exploit missing validation of strchr() return values in the CONNECT and GET proxy handling paths to trigger null pointer dereferences and crash the server when httpd and proxy features are enabled.

LibVNCServer versions 0.9.15 and prior (fixed in commit 009008e) contain a heap out-of-bounds read vulnerability in the UltraZip encoding handler that allows a malicious VNC server to cause information disclosure or application crash. Attackers can exploit improper bounds checking in the HandleUltraZipBPP() function by manipulating subrectangle header counts to read beyond the allocated heap buffer.

libvncclient v0.9.13 was discovered to contain a memory leak via the function rfbClientCleanup().

It was discovered that websockets.c in LibVNCServer prior to 0.9.12 did not properly decode certain WebSocket frames. A malicious attacker could exploit this by sending specially crafted WebSocket frames to a server, causing a heap-based buffer overflow.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/scale.c has a pixel_value integer overflow.

An issue was discovered in LibVNCServer before 0.9.13. libvncclient/rfbproto.c does not limit TextChat size.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rre.c allows out-of-bounds access via encodings.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/hextile.c allows out-of-bounds access via encodings.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/corre.c allows out-of-bounds access via encodings.

An issue was discovered in LibVNCServer before 0.9.13. There is an information leak (of uninitialized memory contents) in the libvncclient/rfbproto.c ConnectToRFBRepeater function.

libvncclient/sockets.c in LibVNCServer before 0.9.13 has a buffer overflow via a long socket filename.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/ws_decode.c can lead to a crash because of unaligned accesses in hybiReadAndDecode.

An issue was discovered in LibVNCServer before 0.9.13. libvncclient/tls_openssl.c has a NULL pointer dereference.

An issue was discovered in LibVNCServer before 0.9.13. libvncserver/rfbregion.c has a NULL pointer dereference.

An issue was discovered in LibVNCServer before 0.9.13. An improperly closed TCP connection causes an infinite loop in libvncclient/sockets.c.

An issue was discovered in LibVNCServer before 0.9.13. Byte-aligned data is accessed through uint32_t pointers in libvncclient/rfbproto.c. NOTE: there is reportedly "no trust boundary crossed.

An issue was discovered in LibVNCServer before 0.9.13. Byte-aligned data is accessed through uint16_t pointers in libvncserver/translate.c. NOTE: Third parties do not consider this to be a vulnerability as there is no known path of exploitation or cross of a trust boundary

libvncclient/cursor.c in LibVNCServer through 0.9.12 has a HandleCursorShape integer overflow and heap-based buffer overflow via a large height or width value. NOTE: this may overlap CVE-2019-15690.

LibVNC commit before d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a contains a memory leak (CWE-655) in VNC server code, which allow an attacker to read stack memory and can be abused for information disclosure. Combined with another vulnerability, it can be used to leak stack memory and bypass ASLR. This attack appear to be exploitable via network connectivity. These vulnerabilities have been fixed in commit d01e1bb4246323ba6fcee3b82ef1faa9b1dac82a.

LibVNC through 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

LibVNC before 0.9.12 contains a heap out-of-bounds write vulnerability in libvncserver/rfbserver.c. The fix for CVE-2018-15127 was incomplete.

LibVNC before 0.9.12 contains multiple heap out-of-bounds write vulnerabilities in libvncclient/rfbproto.c. The fix for CVE-2018-20019 was incomplete.

LibVNC before commit ca2a5ac02fbbadd0a21fabba779c1ea69173d10b contains heap use-after-free vulnerability in server code of file transfer extension that can result remote code execution.

An issue was discovered in LibVNCServer through 0.9.11. rfbProcessClientNormalMessage() in rfbserver.c does not sanitize msg.cct.length, leading to access to uninitialized and potentially sensitive data or possibly unspecified other impact (e.g., an integer overflow) via specially crafted VNC packets.

Heap-based buffer overflow in rfbproto.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message containing a subrectangle outside of the client drawing area.

Heap-based buffer overflow in ultra.c in LibVNCClient in LibVNCServer before 0.9.11 allows remote servers to cause a denial of service (application crash) or possibly execute arbitrary code via a crafted FramebufferUpdate message with the Ultra type tile, such that the LZO payload decompressed length exceeds what is specified by the tile dimensions.