The CIL compiler in SELinux 3.2 has a use-after-free in __cil_verify_classperms (called from __cil_verify_classpermission and __cil_pre_verify_helper). References: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=31065 https://github.com/google/oss-fuzz-vulns/blob/main/vulns/selinux/OSV-2021-417.yaml Upstream patch: https://github.com/SELinuxProject/selinux/commit/f34d3d30c8325e4847a6b696fe7a3936a8a361f3
Created libsepol tracking bugs for this issue: Affects: fedora-all [bug 1979663]
selinux/libsepol is mostly local access and to perform this attack would require local access as compared to network access. An attacker would also require some form of privileges to write the policy file and compile the CIL. The availability impact is also low as this flaw would not cause a system wide or complete lack of availability. Instead the attack would only impact availability of selinux temporarily.
This issue has been addressed in the following products: Red Hat Enterprise Linux 8 Via RHSA-2021:4513 https://access.redhat.com/errata/RHSA-2021:4513
This bug is now closed. Further updates for individual products will be reflected on the CVE page(s): https://access.redhat.com/security/cve/cve-2021-36084