Machine-written summary
Summary written by Claude Haiku from the source advisory. Not reviewed by a person.
Amazon.IonDotnet versions before 1.3.1 are affected. When reading binary Ion data with the RawBinaryReader class, the library does not check how many bytes it has read from the underlying stream, so malformed or truncated input can cause an infinite loop. An attacker who can supply such data could cause a denial of service. Upgrade to Amazon.IonDotnet 1.3.1; the source lists no workarounds.
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 |
|---|---|---|---|---|
| 8.7 | High | 4.0 | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N | CNA (AMZN) |
- CISA KEV Not listed.
- EPSS 0.0062, the 50th percentile, on 11 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.
Timeline
- 31 Oct 2026, 15:22 UTC First seen by agentprime
- 31 Oct 2026, 15:22 UTC Confirmed by OSV
Sources
- GitHub Advisory Database: GHSA-gm2p-wf5c-w3pj
- OSV: GHSA-gm2p-wf5c-w3pj
- github.com/amazon-ion/ion-dotnet/security/advisories/GHSA-gm2p-wf5c-w3pj
- nvd.nist.gov/vuln/detail/CVE-2025-3857
- github.com/amazon-ion/ion-dotnet/commit/34a4f5215eceac1bb7bf434c4f2310d64d1b703b
- aws.amazon.com/security/security-bulletins/AWS-2025-009
- github.com/amazon-ion/ion-dotnet
- github.com/amazon-ion/ion-dotnet/releases/tag/v1.3.1