FSF GNU glibc unsetenv Vulnerability
BID:648
Info
FSF GNU glibc unsetenv Vulnerability
| Bugtraq ID: | 648 |
| Class: | Unknown |
| CVE: | |
| Remote: | No |
| Local: | Yes |
| Published: | Sep 17 1999 12:00AM |
| Updated: | Sep 17 1999 12:00AM |
| Credit: | This vulnerability was found by Tymm Twillman <[email protected]>. |
| Vulnerable: |
GNU glibc 2.1.1 |
| Not Vulnerable: |
GNU glibc 2.1.2 |
Discussion
FSF GNU glibc unsetenv Vulnerability
An error in the 'unsetenv' function in glibc 2.1.1 causes it to fail to unset the requested environment variable if the variable is present twice consecutively in the environment array. 'unsetenv' will destroy the first instance of it but not the second one.
This represents a vulnerability as unsetenv is sometimes used by programs that depend on it to unset possibly dangerous environment variables. One such program is ld.so. This means that a malicious user could define his own LD_* environment variables which although would not affect setuid programs would affect programs executed by the setuid application.
An error in the 'unsetenv' function in glibc 2.1.1 causes it to fail to unset the requested environment variable if the variable is present twice consecutively in the environment array. 'unsetenv' will destroy the first instance of it but not the second one.
This represents a vulnerability as unsetenv is sometimes used by programs that depend on it to unset possibly dangerous environment variables. One such program is ld.so. This means that a malicious user could define his own LD_* environment variables which although would not affect setuid programs would affect programs executed by the setuid application.
References
FSF GNU glibc unsetenv Vulnerability
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