vulnerability / NVI-00018284 / Revision 1
Nerdbank.MessagePack has a memory amplification DoS in collection deserialization
GitHub lists this reviewed advisory for Nerdbank.MessagePack. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
5.3 medium
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
Nerdbank.MessagePack
source listed< 1.1.78
Nerdbank.MessagePack deserializers for many collection-shaped types trusted the element count declared in MessagePack array and map headers when allocating destination storage. A crafted payload could therefore force large arrays, pooled buffers, dictionaries, or collection instances to be allocated before the deserializer had consumed the corresponding elements. The same allocation pattern existed across strongly typed arrays, primitive arrays, mutable and immutable dictionaries, mutable enumerables, span-backed enumerable construction, `JsonNode`, `MessagePackValue`, and the object/dynamic primitive converters. Because MessagePack array and map headers carry an attacker-controlled element count, any converter that immediately allocates `count` elements or constructs a collection with capacity `count` can turn a payload that is merely large into a much larger managed heap allocation. The reader's residency checks reduce the most extreme header-only attack shape, but they do not remove the memory amplification: minimal MessagePack elements can be one or two bytes on the wire while the managed representation may require object references, dictionary buckets, entries, array headers
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
Each assertion retains its source. Mirrored records may repeat one underlying publisher; additional links are not independent corroboration.
- GHSA-qjvr-435c-5fjh ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
First indexed by Null; source disclosure date is shown separately.