Snappier 1.1.0 Decompression memory corruption

Summaryinfo

A vulnerability was found in Snappier 1.1.0. It has been rated as critical. Affected by this vulnerability is an unknown functionality of the component Decompression Handler. The manipulation leads to memory corruption. This vulnerability is uniquely identified as CVE-2023-28638. The attack is possible to be carried out remotely. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability, which was classified as critical, has been found in Snappier 1.1.0. This issue affects an unknown function of the component Decompression Handler. The manipulation with an unknown input leads to a memory corruption vulnerability. Using CWE to declare the problem leads to CWE-119. The product performs operations on a memory buffer, but it can read from or write to a memory location that is outside of the intended boundary of the buffer. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

Snappier is a high performance C# implementation of the Snappy compression algorithm. This is a buffer overrun vulnerability that can affect any user of Snappier 1.1.0. In this release, much of the code was rewritten to use byte references rather than pointers to pinned buffers. This change generally improves performance and reduces workload on the garbage collector. However, when the garbage collector performs compaction and rearranges memory, it must update any byte references on the stack to refer to the updated location. The .NET garbage collector can only update these byte references if they still point within the buffer or to a point one byte past the end of the buffer. If they point outside this area, the buffer itself may be moved while the byte reference stays the same. There are several places in 1.1.0 where byte references very briefly point outside the valid areas of buffers. These are at locations in the code being used for buffer range checks. While the invalid references are never dereferenced directly, if a GC compaction were to occur during the brief window when they are on the stack then it could invalidate the buffer range check and allow other operations to overrun the buffer. This should be very difficult for an attacker to trigger intentionally. It would require a repetitive bulk attack with the hope that a GC compaction would occur at precisely the right moment during one of the requests. However, one of the range checks with this problem is a check based on input data in the decompression buffer, meaning malformed input data could be used to increase the chance of success. Note that any resulting buffer overrun is likely to cause access to protected memory, which will then cause an exception and the process to be terminated. Therefore, the most likely result of an attack is a denial of service. This issue has been patched in release 1.1.1. Users are advised to upgrade. Users unable to upgrade may pin buffers to a fixed location before using them for compression or decompression to mitigate some, but not all, of these cases. At least one temporary decompression buffer is internal to the library and never pinned.

The weakness was disclosed 03/28/2023 as GHSA-838x-pcvx-6p5w. It is possible to read the advisory at github.com. The identification of this vulnerability is CVE-2023-28638 since 03/20/2023. The technical details are unknown and an exploit is not publicly available.

Upgrading to version 1.1.1 eliminates this vulnerability. Applying the patch d7ac5267b5b18439e6d108f8138edf48c436b32f is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Name

• Snappier

Version

• 1.1.0

License

• open-source

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CPE 2.2info

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