Executive brief
iperf3 is a network bandwidth measurement tool widely used for testing network performance. A remote attacker can crash the iperf3 service by sending specially crafted messages that trigger unlimited memory allocation, causing the application to exhaust available system memory and become unavailable.
Technical details
The vulnerability exists in the JSON_read() function, which accepts a peer-controlled message length parameter and allocates memory without enforcing an upper bound (CWE-789). An unauthenticated remote attacker can exploit this over the network by sending messages with artificially large length values, triggering excessive memory consumption before any authentication checks occur. This results in Denial of Service through memory exhaustion, severe slowdown, or termination of the iperf3 service. Mitigation includes restricting network access to the iperf3 control port and enforcing process-level memory limits; a patch has been released in upstream iperf3 (commit 0128d0357b7e8916fe39e980e455729bc0e5fd4e).
Affected products
- ESnet iperf3 <unknown
Timeline
- 2026-08-11: disclosed