CVE-2020-14402 (published 2020-06-17T16:15Z)

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

Severity: MEDIUM
CVSS v2 base score: 5.5 (AV:N/AC:L/Au:S/C:P/I:N/A:P)
CVSS v3 base score: 5.4, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:L)

Weakness information:
cwe_id: CWE-787
cwe_name: Out-of-bounds Write
description: The product writes data past the end, or before the beginning, of the intended buffer.
extended_description: 
            
            
             
			 
         
         

Fix information:
repo_url: https://github.com/LibVNC/libvncserver
commit_details: repo_url: https://github.com/LibVNC/libvncserver
author: Tobias Junghans
author_date: 2020-05-27 12:13:48+02:00
msg: libvncserver: encodings: prevent OOB accesses
repository: repo_url: https://github.com/LibVNC/libvncserver
repo_name: LibVNC/libvncserver
description: LibVNCServer/LibVNCClient are cross-platform C libraries that allow you to easily implement VNC server or client functionality in your program.
repo_language: C
owner: LibVNC
file_changes: filename: corre.c
change_type: ModificationType.MODIFY
diff: @@ -233,7 +233,7 @@ subrectEncode##bpp(rfbClientPtr client, uint##bpp##_t *data, int w, int h) {
             seg = data+(j*w);                                                 \
             if (seg[x] != cl) {break;}                                        \
             i = x;                                                            \
-            while ((seg[i] == cl) && (i < w)) i += 1;                         \
+            while ((i < w) && (seg[i] == cl)) i += 1;                         \
             i -= 1;                                                           \
             if (j == y) vx = hx = i;                                          \
             if (i < vx) vx = i;                                               \

programming_language: C
filename: hextile.c
change_type: ModificationType.MODIFY
diff: @@ -224,7 +224,7 @@ subrectEncode##bpp(rfbClientPtr cl, uint##bpp##_t *data, int w, int h,
                     seg = data+(j*w);                                           \
                     if (seg[x] != cl2) {break;}                                 \
                     i = x;                                                      \
-                    while ((seg[i] == cl2) && (i < w)) i += 1;                  \
+                    while ((i < w) && (seg[i] == cl2)) i += 1;                  \
                     i -= 1;                                                     \
                     if (j == y) vx = hx = i;                                    \
                     if (i < vx) vx = i;                                         \

programming_language: C
filename: rre.c
change_type: ModificationType.MODIFY
diff: @@ -200,7 +200,7 @@ static int                                                                    \
             seg = data+(j*w);                                                 \
             if (seg[x] != cl) {break;}                                        \
             i = x;                                                            \
-            while ((seg[i] == cl) && (i < w)) i += 1;                         \
+            while ((i < w) && (seg[i] == cl)) i += 1;                         \
             i -= 1;                                                           \
             if (j == y) vx = hx = i;                                          \
             if (i < vx) vx = i;                                               \

programming_language: C