CVE-2026-107300
msgpack5: Many buffered values can exhaust the streaming decoder stack
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Exploit likelihood
What each source reports
CVE List Score used
7.5
msgpack5: Many buffered values can exhaust the streaming decoder stack
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
- Record
CVE-2026-107300- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674
- Updated
- 2026-11-02
EUVDEUVD-2026-95111
7.5
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
- Record
EUVD-2026-95111- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-5x5g-h9x8-2fh9
7.5
msgpack5: Many buffered values can exhaust the streaming decoder stack
Impact
The streaming decoder recursively invokes itself for every complete value remaining in a chunk. A single chunk containing many small valid MessagePack values can exhaust the JavaScript call stack and interrupt the process or stream.
Patches
The streaming decoder now drains concatenated values iteratively with constant call-stack depth.
Workarounds
Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.
- Record
GHSA-5x5g-h9x8-2fh9- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674
- Updated
- 2026-11-02
NVD
7.5
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
- Record
CVE-2026-107300- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674
- Updated
- 2026-11-02
OSV
7.5
msgpack5: Many buffered values can exhaust the streaming decoder stack
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
- Record
CVE-2026-107300- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674
- Updated
- 2026-11-02
OSVGHSA-5x5g-h9x8-2fh9
7.5
msgpack5: Many buffered values can exhaust the streaming decoder stack
Impact
The streaming decoder recursively invokes itself for every complete value remaining in a chunk. A single chunk containing many small valid MessagePack values can exhaust the JavaScript call stack and interrupt the process or stream.
Patches
The streaming decoder now drains concatenated values iteratively with constant call-stack depth.
Workarounds
Limit the number of MessagePack values accepted in one chunk, or split large batches before passing them to the decoder stream.
- Record
GHSA-5x5g-h9x8-2fh9- CVSS 3.1
- 7.5 High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-674
- Updated
- 2026-11-02
OSVAZL-106851 No score
CVE-2026-107300 affecting package msgpack 3.3.0-1
msgpack5 is a msgpack v5 implementation for node.js and the browser. Prior to 6.1.0, the streaming decoder recursively invokes itself for each complete MessagePack value remaining in a chunk. A remote peer can send one chunk containing many small valid values, causing recursion proportional to the value count, exhausting the JavaScript call stack, and interrupting the process or stream. This issue is fixed in version 6.1.0.
- Record
AZL-106851- Updated
- 2026-11-02
OSVCLSA-2026-1791806348 No score
TuxCare security update for msgpack5 (5 CVEs)
TuxCare rebuilt msgpack5 to address 5 CVEs. Fixed in 4.5.1-tuxcare.1.
- Record
CLSA-2026-1791806348- Updated
- 2026-11-02
OSVCLSA-2026-1793302953 No score
TuxCare security update for msgpack5 (7 CVEs)
TuxCare rebuilt msgpack5 to address 7 CVEs. Fixed in 3.6.1-tuxcare.1.
- Record
CLSA-2026-1793302953- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
msgpack5npm |
before 6.1.0 | 6.1.0 |
msgpackAzure Linux:3 |
through 3.3.0-1 | None known |
msgpack5TuxCare:npm From an advisory covering 5 CVEs |
4.5.1-tuxcare.0 up to 4.5.1-tuxcare.1, plus listed versions 4.5.1 |
4.5.1-tuxcare.1 |
msgpack5TuxCare:npm From an advisory covering 7 CVEs |
3.6.1-tuxcare.0 up to 3.6.1-tuxcare.1, plus listed versions 3.6.1 |
3.6.1-tuxcare.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| affected, facts | ||
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-107300 is a high vulnerability (CVSS 7.5) in Mcollina Msgpack5, published October 8, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.43%, the 37th percentile. Fixed in msgpack5 6.1.0.
References
github.com/mcollina/msgpack5/security/advisories/GHSA-5x5g-h9x8-2fh9
github.com/mcollina/msgpack5/commit/77fbef144d05def5d16fc22c37caa64c0a7efeba
github.com/mcollina/msgpack5/releases/tag/v6.1.0
github.com/advisories/GHSA-5x5g-h9x8-2fh9
nvd.nist.gov/vuln/detail/CVE-2026-107300
github.com/CVEProject/cvelistV5/tree/main/cves/2026/107xxx/CVE-2026-107300.json
github.com/mcollina/msgpack5