Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The npm package msgpack5 is vulnerable in versions before 6.1.0. Decoding a negative signed 64-bit integer changes the bytes of the caller's input buffer, and positive integers and other value types are not affected. An attacker is not described as needing any particular access; the risk is that applications that keep or reuse the encoded input may silently see corrupted data. Upgrade to msgpack5 6.1.0, which computes these values without writing to the input buffer, or copy input before decoding it.
Not analysed yet
We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.
Severity and exploitation
| Score | Rating | CVSS | Vector | Source |
|---|---|---|---|---|
| 3.7 | Low | 3.1 | CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N | CNA (GitHub_M) |
- CISA KEV Not listed.
- EPSS 0.0028, the 20th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 13:33 UTC First seen by agentprime
- 31 Oct 2026, 13:33 UTC Confirmed by OSV