NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a locking inconsistency vulnerability that when certain conditions are met (multi-threaded, RPZ XFR reload, RPZ zone with rpz-nsip/rpz-nsdname triggers) it could result in heap use-after-free and eventual crash. An adversary can exploit the vulnerability if conditions are first met on a vulnerable Unbound, i.e., multi-threaded, an RPZ zone with rpz-nsip/rpz-nsdname triggers and an ongoing XFR for that RPZ zone. Local RPZ files do not trigger the vulnerability. If the timing is right and an XFR happens at the same time another thread needs to read that RPZ zone, the reader may not hold the lock long enough and the thread applying the XFR may free objects that the reader is about to walk causing the use-after-free. Unbound 1.25.1 contains a patch with a fix to the locking code.
Weakness
The product does not lock or does not correctly lock a resource when the product must have exclusive access to the resource.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Unbound | Nlnetlabs | 1.14.0 (including) | 1.25.1 (excluding) |
| Red Hat Hardened Images | RedHat | unbound-main-1.25.1-0.1.hum1 | * |
| Unbound | Ubuntu | devel | * |
| Unbound | Ubuntu | esm-infra/xenial | * |
| Unbound | Ubuntu | noble | * |
| Unbound | Ubuntu | questing | * |
| Unbound | Ubuntu | resolute | * |