{"items":[{"id":"NVI-00017733","kind":"vulnerability","title":"MessagePack-CSharp: LZ4 decompression allocates from unbounded declared output lengths","revision":1,"unknowns":["Customer inventory, deployment, reachability and exploitation have not been inspected."],"lifecycle":"active","identifiers":["GHSA-v72x-2h86-7f8m","CVE-2026-48510"],"plain_summary":"GitHub lists this reviewed advisory for MessagePack, MessagePack. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.","review_status":"source_listed","control_topics":[],"public_actions":[{"summary":"Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.","source_ids":["sr-51dc11fa6861ec28faa7c7c6457031cc"],"action_type":"investigate","limitations":"Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system.","current_supported_target":null}],"schema_version":"1.1.0","source_metrics":[{"kind":"CVSS","as_of":"2026-06-25T18:53:45.000Z","value":"7.5 medium","meaning":"GitHub source severity; exploitability and local consequence require separate evidence.","source_id":"sr-51dc11fa6861ec28faa7c7c6457031cc"}],"why_it_matters":"Published affected context helps an owner decide what evidence to gather. This report has not examined your application.","related_sources":[{"id":"sr-51dc11fa6861ec28faa7c7c6457031cc","url":"https://github.com/advisories/GHSA-v72x-2h86-7f8m","basis":"vendor_advisory","notes":"GitHub Advisory Database; CC-BY-4.0. Each advisory links its original attribution. Null normalizes fields.","title":"GHSA-v72x-2h86-7f8m","publisher":"GitHub Advisory Database","observed_at":"2026-11-05T19:05:53.922Z"}],"affected_context":[{"certainty":"source_listed","source_ids":["sr-51dc11fa6861ec28faa7c7c6457031cc"],"technology":"MessagePack","known_exclusions":[],"conditions_summary":"## Summary\n\nWhen MessagePack-CSharp decompresses `Lz4Block` or `Lz4BlockArray` payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable.\n\nA small payload can claim a very large uncompressed length and force a large allocation before LZ4 decoding begins.\n\n## Impact\n\nApplications are affected when they deserialize attacker-controlled MessagePack payloads with `MessagePackCompression.Lz4Block` or `MessagePackCompression.Lz4BlockArray` enabled.\n\nIn the `Lz4Block` case, an attacker-controlled integer is used to request the destination span. In the `Lz4BlockArray` case, per-block uncompressed lengths and their aggregate can be attacker-controlled. Without a cap, the declared output size can be disproportionate to the input size, producing out-of-memory exceptions, process termination on constrained hosts, or severe memory pressure.\n\nThis advisory is about unbounded allocation from declared decompressed sizes. It is separate from the LZ4 source-buffer over-read issue, which concerns unsafe decoder reads beyond the compressed input buffe","public_affected_ranges":["< 2.5.301"]},{"certainty":"source_listed","source_ids":["sr-51dc11fa6861ec28faa7c7c6457031cc"],"technology":"MessagePack","known_exclusions":[],"conditions_summary":"## Summary\n\nWhen MessagePack-CSharp decompresses `Lz4Block` or `Lz4BlockArray` payloads, it reads declared uncompressed lengths from the wire and allocates output buffers based on those lengths before validating that the compressed data is valid or that the declared expansion is reasonable.\n\nA small payload can claim a very large uncompressed length and force a large allocation before LZ4 decoding begins.\n\n## Impact\n\nApplications are affected when they deserialize attacker-controlled MessagePack payloads with `MessagePackCompression.Lz4Block` or `MessagePackCompression.Lz4BlockArray` enabled.\n\nIn the `Lz4Block` case, an attacker-controlled integer is used to request the destination span. In the `Lz4BlockArray` case, per-block uncompressed lengths and their aggregate can be attacker-controlled. Without a cap, the declared output size can be disproportionate to the input size, producing out-of-memory exceptions, process termination on constrained hosts, or severe memory pressure.\n\nThis advisory is about unbounded allocation from declared decompressed sizes. It is separate from the LZ4 source-buffer over-read issue, which concerns unsafe decoder reads beyond the compressed input buffe","public_affected_ranges":[">= 3.0, < 3.1.7"]}],"null_published_at":"2026-11-05T19:10:21.458Z","source_updated_at":"2026-06-25T18:53:45.000Z","source_disclosed_at":"2026-06-25T18:53:44.000Z","is_synthetic_fixture":false,"null_last_reviewed_at":null,"public_change_summary":"First indexed by Null; source disclosure date is shown separately.","null_first_observed_at":"2026-11-05T19:05:53.922Z"}],"next_cursor":null,"snapshot_revision":"42594"}