A use-after-free issue was discovered in libwebm through 2018-02-02. If a Vp9HeaderParser was initialized once before, its property frame_ would not be changed because of code in vp9parser::Vp9HeaderParser::SetFrame. Its frame_ could be freed while the corresponding pointer would not be updated, leading to a dangling pointer. This is related to the function OutputCluster in webm_info.cc.
Weakness
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Libwebm | Webmproject | * | 1.0.0.27 (including) |
| Chromium-browser | Ubuntu | artful | * |
| Chromium-browser | Ubuntu | bionic | * |
| Chromium-browser | Ubuntu | cosmic | * |
| Chromium-browser | Ubuntu | devel | * |
| Chromium-browser | Ubuntu | trusty | * |
| Chromium-browser | Ubuntu | xenial | * |
| Oxide-qt | Ubuntu | artful | * |
| Oxide-qt | Ubuntu | esm-infra/xenial | * |
| Oxide-qt | Ubuntu | trusty | * |
| Oxide-qt | Ubuntu | xenial | * |
Potential Mitigations
References
- https://bugs.chromium.org/p/webm/issues/detail?id=1493
- https://github.com/dwfault/PoCs/blob/master/libwebm%20Vp9HeaderParser%20UAF%20by%20PrintVP9Info/libwebm%20Vp9HeaderParser%20UAF%20by%20PrintVP9Info.md
- https://bugs.chromium.org/p/webm/issues/detail?id=1493
- https://github.com/dwfault/PoCs/blob/master/libwebm%20Vp9HeaderParser%20UAF%20by%20PrintVP9Info/libwebm%20Vp9HeaderParser%20UAF%20by%20PrintVP9Info.md