CVE-2023-4736 (published 2023-09-02T19:15Z)

Untrusted Search Path in GitHub repository vim/vim prior to 9.0.1833.

CVSS v3 base score: 7.8, HIGH (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H)

Weakness information:
cwe_id: CWE-426
cwe_name: Untrusted Search Path
description: The product searches for critical resources using an externally-supplied search path that can point to resources that are not under the product's direct control.
extended_description: 
            This might allow attackers to execute their own programs, access unauthorized data files, or modify configuration in unexpected ways. If the product uses a search path to locate critical resources such as programs, then an attacker could modify that search path to point to a malicious program, which the targeted product would then execute. The problem extends to any type of critical resource that the product trusts.
            Some of the most common variants of untrusted search path are:
               
                  In various UNIX and Linux-based systems, the PATH environment variable may be consulted to locate executable programs, and LD_PRELOAD may be used to locate a separate library.
                  In various Microsoft-based systems, the PATH environment variable is consulted to locate a DLL, if the DLL is not found in other paths that appear earlier in the search order.
               
         
         

Fix information:
repo_url: https://github.com/vim/vim
commit_details: repo_url: https://github.com/vim/vim
author: Christian Brabandt
author_date: 2023-08-31 23:52:30+02:00
msg: patch 9.0.1833: [security] runtime file fixes

Problem:  runtime files may execute code in current dir
Solution: only execute, if not run from current directory

The perl, zig and ruby filetype plugins and the zip and gzip autoload
plugins may try to load malicious executable files from the current
working directory.  This is especially a problem on windows, where the
current directory is implicitly in your $PATH and windows may even run a
file with the extension `.bat` because of $PATHEXT.

So make sure that we are not trying to execute a file from the current
directory. If this would be the case, error out (for the zip and gzip)
plugins or silently do not run those commands (for the ftplugins).

This assumes, that only the current working directory is bad. For all
other directories, it is assumed that those directories were
intentionally set to the $PATH by the user.

Signed-off-by: Christian Brabandt <cb@256bit.org>
repository: repo_url: https://github.com/vim/vim
repo_name: vim/vim
description: The official Vim repository
repo_language: Vim Script
owner: vim
file_changes: filename: gzip.vim
change_type: ModificationType.MODIFY
diff: @@ -10,12 +10,17 @@
 fun s:check(cmd)
   let name = substitute(a:cmd, '\(\S*\).*', '\1', '')
   if !exists("s:have_" . name)
+    " safety check, don't execute anything from the current directory
+    let f = fnamemodify(exepath(name), ":p:h") !=# getcwd()
+    if !f
+      echoerr "Warning: NOT executing " .. name .. " from current directory!"
+    endif
     let e = executable(name)
     if e < 0
       let r = system(name . " --version")
       let e = (r !~ "not found" && r != "")
     endif
-    exe "let s:have_" . name . "=" . e
+    exe "let s:have_" . name . "=" . (e && f)
   endif
   exe "return s:have_" . name
 endfun

programming_language: Lua
filename: zip.vim
change_type: ModificationType.MODIFY
diff: @@ -57,6 +57,10 @@ if !exists("g:zip_extractcmd")
  let g:zip_extractcmd= g:zip_unzipcmd
 endif
 
+if fnamemodify(exepath(g:zip_unzipcmd), ":p:h") ==# getcwd()
+ echoerr "Warning: NOT executing " .. g:zip_unzipcmd .. " from current directory!"
+ finish
+endif
 " ----------------
 "  Functions: {{{1
 " ----------------

programming_language: Lua
filename: perl.vim
change_type: ModificationType.MODIFY
diff: @@ -54,7 +54,8 @@ endif
 
 " Set this once, globally.
 if !exists("perlpath")
-    if executable("perl")
+    " safety check: don't execute perl from current directory
+    if executable("perl") && fnamemodify(exepath("perl"), ":p:h") != getcwd()
       try
 	if &shellxquote != '"'
 	    let perlpath = system('perl -e "print join(q/,/,@INC)"')

programming_language: Batchfile
filename: ruby.vim
change_type: ModificationType.MODIFY
diff: @@ -99,41 +99,51 @@ function! s:build_path(path) abort
   return path
 endfunction
 
-if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
-  let s:version_file = findfile('.ruby-version', '.;')
-  if !empty(s:version_file) && filereadable(s:version_file)
-    let b:ruby_version = get(readfile(s:version_file, '', 1), '')
-    if !has_key(g:ruby_version_paths, b:ruby_version)
-      let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
+let s:execute_ruby = 1
+" Security Check, don't execute ruby from the current directory
+if fnamemodify(exepath("ruby"), ":p:h") ==# getcwd()
+  let s:execute_ruby = 0
+endif
+
+function SetRubyPath()
+  if !exists('b:ruby_version') && !exists('g:ruby_path') && isdirectory(expand('%:p:h'))
+    let s:version_file = findfile('.ruby-version', '.;')
+    if !empty(s:version_file) && filereadable(s:version_file) && s:execute_ruby
+      let b:ruby_version = get(readfile(s:version_file, '', 1), '')
+      if !has_key(g:ruby_version_paths, b:ruby_version)
+	let g:ruby_version_paths[b:ruby_version] = s:query_path(fnamemodify(s:version_file, ':p:h'))
+      endif
     endif
   endif
-endif
 
-if exists("g:ruby_path")
-  let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
-elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', ''))
-  let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
-  let s:ruby_path = s:build_path(s:ruby_paths)
-else
-  if !exists('g:ruby_default_path')
-    if has("ruby") && has("win32")
-      ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
-    elseif executable('ruby') && !empty($HOME)
-      let g:ruby_default_path = s:query_path($HOME)
-    else
-      let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+  if exists("g:ruby_path")
+    let s:ruby_path = type(g:ruby_path) == type([]) ? join(g:ruby_path, ',') : g:ruby_path
+  elseif has_key(g:ruby_version_paths, get(b:, 'ruby_version', '')) && s:execute_ruby
+    let s:ruby_paths = g:ruby_version_paths[b:ruby_version]
+    let s:ruby_path = s:build_path(s:ruby_paths)
+  else
+    if !exists('g:ruby_default_path')
+      if has("ruby") && has("win32")
+	ruby ::VIM::command( 'let g:ruby_default_path = split("%s",",")' % $:.join(%q{,}) )
+      elseif executable('ruby') && !empty($HOME) && s:execute_ruby
+	let g:ruby_default_path = s:query_path($HOME)
+      else
+	let g:ruby_default_path = map(split($RUBYLIB,':'), 'v:val ==# "." ? "" : v:val')
+      endif
     endif
+    let s:ruby_paths = g:ruby_default_path
+    let s:ruby_path = s:build_path(s:ruby_paths)
   endif
-  let s:ruby_paths = g:ruby_default_path
-  let s:ruby_path = s:build_path(s:ruby_paths)
-endif
 
-if stridx(&l:path, s:ruby_path) == -1
-  let &l:path = s:ruby_path
-endif
-if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
-  let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
-endif
+  if stridx(&l:path, s:ruby_path) == -1
+    let &l:path = s:ruby_path
+  endif
+  if exists('s:ruby_paths') && stridx(&l:tags, join(map(copy(s:ruby_paths),'v:val."/tags"'),',')) == -1
+    let &l:tags = &tags . ',' . join(map(copy(s:ruby_paths),'v:val."/tags"'),',')
+  endif
+endfunction
+
+call SetRubyPath()
 
 if (has("gui_win32") || has("gui_gtk")) && !exists("b:browsefilter")
   let b:browsefilter = "Ruby Source Files (*.rb)\t*.rb\n" .

programming_language: Ruby
filename: zig.vim
change_type: ModificationType.MODIFY
diff: @@ -39,7 +39,9 @@ endif
 
 let &l:define='\v(<fn>|<const>|<var>|^\s*\#\s*define)'
 
-if !exists('g:zig_std_dir') && exists('*json_decode') && executable('zig')
+" Safety check: don't execute zip from current directory
+if !exists('g:zig_std_dir') && exists('*json_decode') &&
+    \  executable('zig') && fnamemodify(exepath("zig"), ":p:h") != getcwd()
     silent let s:env = system('zig env')
     if v:shell_error == 0
         let g:zig_std_dir = json_decode(s:env)['std_dir']

programming_language: Batchfile
filename: version.c
change_type: ModificationType.MODIFY
diff: @@ -699,6 +699,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    1833,
 /**/
     1832,
 /**/

programming_language: Ruby