CVE-2019-19126

On the x86-64 architecture, the GNU C Library (aka glibc) before 2.31 fails to ignore the LD_PREFER_MAP_32BIT_EXEC environment variable during program execution after a security transition, allowing local attackers to restrict the possible mapping addresses for loaded libraries and thus bypass ASLR for a setuid program.

Weakness

The product does not initialize or incorrectly initializes a resource, which might leave the resource in an unexpected state when it is accessed or used.

Affected Software

Potential Mitigations

• Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.
• For example, in Java, if the programmer does not explicitly initialize a variable, then the code could produce a compile-time error (if the variable is local) or automatically initialize the variable to the default value for the variable’s type. In Perl, if explicit initialization is not performed, then a default value of undef is assigned, which is interpreted as 0, false, or an equivalent value depending on the context in which the variable is accessed.

Related Attack Patterns

• https://cwe.mitre.org/data/definitions/26.html
• https://cwe.mitre.org/data/definitions/29.html

References

• https://lists.debian.org/debian-lts-announce/2022/10/msg00021.html
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/4FQ5LC6JOYSOYFPRUZ4S45KL6IP3RPPZ/
• https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/ZFJ5E7NWOL6ROE5QVICHKIOUGCPFJVUH/
• https://sourceware.org/bugzilla/show_bug.cgi?id=25204
• https://usn.ubuntu.com/4416-1/