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CVE-2026-107297— msgpack5: Quadratic parsing in the streaming decoder

Quick assessment

Affected
mcollina msgpack5
Exploitation
No confirmed in-the-wild exploitation; assess based on exposure
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

msgpack5 是一个适用于 Node.js 和浏览器的 MessagePack v5 实现。在版本 6.1.0 之前，流式解码器在每次收到新的数据块时，都会从开头重新解析未完成的数组或映射。远程对端可以将一个有效的 MessagePack 容器分割成许多小数据块发送，导致已完成的元素被反复解码，从而引发二次方级别的 CPU 占用，并阻塞事件循环。该问题已在 6.1.0 版本中修复。

CVSS 5.9 · Medium

Possible ATT&CK Techniques 1 AI

T1499 · Endpoint Denial of Service

Affected Version Matrix 1

VendorProduct Version RangeStatus
mcollina msgpack5 < 6.1.0 affected
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I. Basic Information for CVE-2026-107297

Vulnerability Information
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Vulnerability Title
msgpack5: Quadratic parsing in the streaming decoder
Source: CVE Program / CVE List V5
Vulnerability Description
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder reparses an incomplete array or map from the beginning whenever another chunk arrives. A remote peer can split one valid MessagePack container across many small chunks, causing completed elements to be decoded repeatedly, producing quadratic CPU use and blocking the event loop. This issue is fixed in version 6.1.0.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H
Source: CVE Program / CVE List V5
Vulnerability Type
算法复杂性
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
mcollina msgpack5 < 6.1.0 -

II. Public POCs for CVE-2026-107297

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III. Intelligence Information for CVE-2026-107297

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Other References for CVE-2026-107297 (3)

Same Patch Batch · mcollina · 2026-10-08 · 7 CVEs total

CVE-2026-107300 7.5 HIGH msgpack5: Many buffered values can exhaust the streaming decoder stack
CVE-2026-107302 7.5 HIGH msgpack5: Truncated map32 headers throw an unexpected error
CVE-2026-107301 6.5 MEDIUM msgpack5: Partial options disable prototype protection
CVE-2026-107299 5.9 MEDIUM msgpack5: Reserved byte can cause unbounded stream buffering
CVE-2026-107298 5.3 MEDIUM msgpack5: Deeply nested input can exhaust the decoder stack
CVE-2026-107296 3.7 LOW msgpack5: Decoding negative int64 values mutates the input buffer

IV. Related Vulnerabilities

Same product: msgpack5
Same vendor: mcollina
Same weakness: CWE-407

V. Comments for CVE-2026-107297

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