ALPINE-CVE-2025-5994
Record from OSV · Published July 16, 2025
A multi-vendor cache poisoning vulnerability named 'Rebirthday Attack' has been discovered in caching resolvers that support EDNS Client Subnet (ECS). Unbound is also vulnerable when compiled with ECS support, i.e., '--enable-subnet', AND configured to send ECS information along with queries to upstream name servers, i.e., at least one of the 'send-client-subnet', 'client-subnet-zone' or 'client-subnet-always-forward' options is used. Resolvers supporting ECS need to segregate outgoing queries to accommodate for different outgoing ECS information. This re-opens up resolvers to a birthday paradox attack (Rebirthday Attack) that tries to match the DNS transaction ID in order to cache non-ECS poisonous replies.
Fixed versions
Upgrade to a fixed version or later. Language registries are listed first, then Linux distributions, then vendor products.
| Package | Ecosystem | Fixed in |
|---|---|---|
| unbound | Alpine:v3.23 | 1.23.1-r0 |
| unbound | Alpine:v3.19 | 1.20.0-r2 |
| unbound | Alpine:v3.21 | 1.22.0-r1 |
| unbound | Alpine:v3.22 | 1.23.1-r0 |
| unbound | Alpine:v3.20 | 1.20.0-r2 |
| unbound | Alpine:v3.24 | 1.23.1-r0 |
Risk scores
Affected products
| Vendor | Product | Versions |
|---|---|---|
| Alpine:v3.23 | unbound | 1.13.0-r1, 1.16.0-r0, 1.5.10-r0 |
| Alpine:v3.19 | unbound | 1.9.1-r0, 0, 1.10.0-r0 |
| Alpine:v3.21 | unbound | 1.5.6-r4, 0, 1.10.0-r0 |
| Alpine:v3.22 | unbound | 1.13.0-r3, 1.13.1-r0, 1.13.1-r1 |
| Alpine:v3.20 | unbound | 1.19.1-r0, 1.13.0-r1, 1.4.13-r3 |
| Alpine:v3.24 | unbound | 0 |
Timeline
- Jul 16, 2025 CVE Published
- Jun 15, 2026 CVE Updated
- Aug 8, 2026 Distribution Patch
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