Libevent is an event notification library. Prior to 2.1.13 and 2.2.2-alpha, libevent has a heap out-of-bounds write in bufferevent_sock.c when bufferevent_socket_set_conn_address_ copies a kernel-supplied AF_UNIX peer address into bufferevent_private.conn_address. Release builds compiled with NDEBUG disable the EVUTIL_ASSERT length guard, and the evhttp accept path can pass a 110-byte sockaddr from accept() into the 28-byte field. An unauthenticated local peer able to connect to an AF_UNIX listener can overwrite the adjacent dns_request pointer and heap data, causing memory corruption with confidentiality, integrity, and availability impact. This issue is fixed in versions 2.1.13 and 2.2.2-alpha.
Weakness
The product contains an assert() or similar statement that can be triggered by an attacker, which leads to an application exit or other behavior that is more severe than necessary.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Red Hat Enterprise Linux 10 | RedHat | libevent-0:2.1.13-1.el10_2 | * |
| Red Hat Enterprise Linux 8 | RedHat | libevent-0:2.1.8-11.el8_10 | * |
| Red Hat Enterprise Linux 8 | RedHat | libevent-0:2.1.8-11.el8_10 | * |
| Red Hat Enterprise Linux 9 | RedHat | libevent-0:2.1.13-1.el9_8 | * |
| Red Hat Enterprise Linux 9 | RedHat | libevent-0:2.1.13-1.el9_8 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/jetstack-cert-manager-rhel9:1790223279 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/cert-manager-istio-csr-rhel9:1790223719 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/cert-manager-operator-rhel9:1790272426 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/jetstack-cert-manager-acmesolver-rhel9:1790589998 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/jetstack-cert-manager-rhel9:1790589912 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/cert-manager-istio-csr-rhel9:1790589914 | * |
| Cert Manager support for Red Hat OpenShift release 1.20 | RedHat | cert-manager/cert-manager-operator-rhel9:1790589855 | * |
| Red Hat Hardened Images | RedHat | libevent-main-2.1.12-19.1.hum1 | * |
| Red Hat Update Infrastructure 5 | RedHat | rhui5/cds-kubernetes-rhel9:1790241897 | * |
| Red Hat Update Infrastructure 5 | RedHat | rhui5/cds-rhel9:1790241954 | * |
| Red Hat Update Infrastructure 5 | RedHat | rhui5/haproxy-rhel9:1790241900 | * |
| Red Hat Update Infrastructure 5 | RedHat | rhui5/installer-rhel9:1790241922 | * |
| Red Hat Update Infrastructure 5 | RedHat | rhui5/rhua-rhel9:1790242004 | * |
| Libevent | Ubuntu | esm-infra/bionic | * |
| Libevent | Ubuntu | esm-infra/focal | * |
| Libevent | Ubuntu | jammy | * |
| Libevent | Ubuntu | noble | * |
| Libevent | Ubuntu | resolute | * |
Extended Description
While assertion is good for catching logic errors and reducing the chances of reaching more serious vulnerability conditions, it can still lead to a denial of service. For example, if a server handles multiple simultaneous connections, and an assert() occurs in one single connection that causes all other connections to be dropped, this is a reachable assertion that leads to a denial of service.
Potential Mitigations
References
- https://github.com/libevent/libevent/commit/52057cb33d0c20c0a0453fbabe6c0c96854931b9
- https://github.com/libevent/libevent/commit/ef38f926e9cd1f082416c6fff13587bc1f431d72
- https://github.com/libevent/libevent/releases/tag/release-2.1.13-stable
- https://github.com/libevent/libevent/releases/tag/release-2.2.2-alpha
- https://github.com/libevent/libevent/security/advisories/GHSA-cvq5-vrvr-j338