Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
The .NET runtime packages (Microsoft.NetCore.App.Runtime for several platforms) and Microsoft.Bcl.Memory are affected in versions 9.0.0 through 9.0.13 and 10.0.0 through 10.0.3. A remote attacker without privileges can send malformed Base64Url input that triggers an out-of-bounds read, causing a denial of service. Upgrade to 9.0.14 or 10.0.4, depending on the release line in use.
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 |
|---|---|---|---|---|
| 7.5 | High | 3.1 | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C | CNA (microsoft) |
- CISA KEV Not listed.
- EPSS 0.023, the 83rd percentile, on 10 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 10 Mar 2026, 19:11 UTC Published by the maintainers as a GitHub repository advisory
- 31 Oct 2026, 15:21 UTC First seen by agentprime
- 31 Oct 2026, 15:21 UTC Confirmed by OSV