CVE-2026-81527 NoSQL injection via unquoted constant GroupBy keys in LINQ pipeline translation
Attackers can inject logic into MongoDB queries via unescaped LINQ keys, potentially altering results or exposing unintended data.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-81527?
CVE-2026-81527 is a medium-severity SQL injection vulnerability in MongoDB C# Driver, published on 27 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
A NoSQL/expression injection weakness exists in the LINQ-to-aggregation query translation layer of the MongoDB C# Driver, in both aggregation expression and query filter translation. When application-supplied values are embedded in certain query constructs, special elements contained within those values are not properly escaped before the resulting query is transmitted to the database, so portions of the value may be interpreted by the database as query logic rather than as data. A user able to supply values that an application incorporates into an affected query may thereby cause unintended data to be returned or query results to be altered.
Weakness: CWE-943
Which versions are affected by CVE-2026-81527?
It affects 1 product.
Products include Mongodb C\# Driver.
How do I fix CVE-2026-81527?
No fix has been published for CVE-2026-81527 yet. Limit exposure of the affected software until one is available.
Use parameterised queries everywhere and never build SQL by joining strings. Upgrade affected software first; a web application firewall only buys time. More about SQL injection.
Is CVE-2026-81527 being exploited?
There is no known exploitation of CVE-2026-81527 in the wild and no public exploit code.
Other vulnerabilities in MongoDB C# Driver
- CVE-2026-88026 Regular expression injection via unescaped characters in LINQ query translation in MongoDB C# Driver
- CVE-2026-81529 Connection-option injection via unescaped settings in the canonical MongoDB URL builder
- CVE-2026-81530 KMS master key exposure via unredacted credential serialization in driver settings string
- CVE-2022-48282 Deserializing compromised object with MongoDB .NET/C# Driver may cause remote code execution
- CVE-2026-88025 GridFS data disclosure and deletion via query-operator injection in file IDs in the MongoDB C# Driver
Sources
Also known as GHSA-qvhj-5652-cjrg.