You may download update Joomla 1.5.26 to Joomla 1.5.27 from my site:
Joomla_Pro_1.5.26_to_1.5.27-Stable-Patch_Package.zip
Update history 1.5.27:
Legend:* -> Security Fix
# -> Bug Fix
$ -> Language fix or change
+ -> Addition
^ -> Change
- -> Removed
! -> Note
-------------------- 1.5.27 Stable Release [27-March-2013] ------------------
^ Change knerpi/css files - kill rounded in template.
^ Change system/system.css in order to improve usability.
- Delete unnecessary files (administrator/kherpi/images/h_cherry: j_header_left.png, j_header_left_rtl.png, j_header_middle.png, j_header_right.png, j_header_right_rtl.png)
- Delete unnecessary files (administrator/kherpi/images/h_green: j_header_left.png, j_header_left_rtl.png, j_header_middle.png, j_header_right.png, j_header_right_rtl.png)
- Delete unnecessary files (administrator/kherpi/images/h_teal: j_header_left.png, j_header_left_rtl.png, j_header_middle.png, j_header_right.png, j_header_right_rtl.png)
+ Add two files: administrator/kherpi/images/ login_lock.png, logo-small.png
^ Change cpanel.php, index.php, login.php in the root directory administrator/templates/khepri
^ Change favicon.ico in the kherpi
^ Change administrator/mod_login/mod_login.php
- Remove <meta name="generator" content="Joomla! 1.5 - Open Source Content Management" />