Vulnerability · Published Aug 26, 2026 · Assigned by vmware
CVE-2026-47857Reactor Core windowTimeout fair-backpressure stream hang due to 20-bit index wrap-around
Medium 5.9
In plain English
A medium-severity integer overflow in Reactor Core from Spring. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities).
Severity (CVSS 3.1)5.9Medium
Exploit odds (30 days)0.4%top 69.3% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known
Official description
In Reactor Core, applications that use the Flux.windowTimeout operator with fairBackpressure enabled are vulnerable to a Denial of Service (DoS) condition. Reactor Core 3.8.0 - 3.8.6 Reactor Core 3.5.0 - 3.7.19 Reactor Core 3.4.41 and earlier
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Spring | Reactor Core | 3.8.0 – through 3.8.63.5.0 – through 3.7.190 – through 3.4.41 |
Weakness: CWE-190 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H