MongoDB OOB Heap Read via Malformed BSON CodeWScope
CVE-2026-13077 Published on July 22, 2026
Out-of-Bounds Heap Read in BSON CodeWScope Element Parsing via Malformed BSONColumn Data
A missing bounds check in the BSON CodeWScope element accessors allows an attacker to trigger an out-of-bounds heap read via a crafted aggregation pipeline. The vulnerability can be exploited by an authenticated user by generating a malformed BSONColumn data containing a CodeWScope element, bypassing wire-level BSON validation. When the forged element is decompressed, the unchecked size value is used in pointer arithmetic, causing either a server crash or disclosure of adjacent heap memory contents.
Vulnerability Analysis
CVE-2026-13077 can be exploited with network access, and requires small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a small impact on integrity, and a high impact on availability.
Weakness Type
Out-of-bounds Read
The software reads data past the end, or before the beginning, of the intended buffer. Typically, this can allow attackers to read sensitive information from other memory locations or cause a crash. A crash can occur when the code reads a variable amount of data and assumes that a sentinel exists to stop the read operation, such as a NUL in a string. The expected sentinel might not be located in the out-of-bounds memory, causing excessive data to be read, leading to a segmentation fault or a buffer overflow. The software may modify an index or perform pointer arithmetic that references a memory location that is outside of the boundaries of the buffer. A subsequent read operation then produces undefined or unexpected results.
Products Associated with CVE-2026-13077
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Affected Versions
MongoDB Server:- Version 7.0 and below 7.0.39 is affected.
- Version 8.0 and below 8.0.28 is affected.
- Version 8.2.0 and below 8.2.12 is affected.
- Version 8.3.0 and below 8.3.7 is affected.