VDB-412432 · CVE-2026-101276 · GCVE-0-2026-101276

esnet iperf3 3.21 Watchdog server_timer_proc use after free

CVSS Meta Temp Score CVSS is a standardized scoring system to determine possibilities of attacks. The Temp Score considers temporal factors like disclosure, exploit and countermeasures. The unique Meta Score calculates the average score of different sources to provide a normalized scoring system.	Current Exploit Price (≈) Our analysts are monitoring exploit markets and are in contact with vulnerability brokers. The range indicates the observed or calculated exploit price to be seen on exploit markets. A good indicator to understand the monetary effort required for and the popularity of an attack.	CTI Interest Score Our Cyber Threat Intelligence team is monitoring different web sites, mailing lists, exploit markets and social media networks. The CTI Interest Score identifies the interest of attackers and the security community for this specific vulnerability in real-time. A high score indicates an elevated risk to be targeted for this vulnerability.
7.0	$0-$5k	1.01-

Summaryinfo

A vulnerability was found in esnet iperf3 3.21. It has been declared as critical. This impacts the function server_timer_proc of the component Watchdog. Executing a manipulation can lead to use after free. This vulnerability is tracked as CVE-2026-101276. The attack can be launched remotely. No exploit exists. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in esnet iperf3 3.21. It has been declared as critical. This vulnerability affects the function server_timer_proc of the component Watchdog. The manipulation with an unknown input leads to a use after free vulnerability. The CWE definition for the vulnerability is CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

iperf3 3.21 (esnet/iperf) contains a remote, unauthenticated heap use-after-free: the server's per-test watchdog server_timer_proc() frees streams without cancelling/joining their worker threads, so a blocked worker dereferences a freed iperf_stream; fixed in 3.22.

The advisory is shared for download at newreleases.io. This vulnerability was named CVE-2026-101276 since 09/28/2026. The exploitation appears to be easy. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are known technical details, but no exploit is available.

Upgrading to version 3.22 eliminates this vulnerability.

VulDB is the best source for vulnerability data and more expert information about this specific topic.

Productinfo

Vendor

esnet

Name

iperf3

Version

3.21

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA CVSS-B Score: 🔒
CNA CVSS-BT Score: 🔒
CNA Vector: 🔒

CVSSv3info

VulDB Meta Base Score: 7.3
VulDB Meta Temp Score: 7.0

VulDB Base Score: 7.3
VulDB Temp Score: 7.0
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

AV	AC	Au	C	I	A
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳
💳	💳	💳	💳	💳	💳

Vector	Complexity	Authentication	Confidentiality	Integrity	Availability
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock
Unlock	Unlock	Unlock	Unlock	Unlock	Unlock

VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Use after free
CWE: CWE-416 / CWE-119
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

0-Day	Unlock	Unlock	Unlock	Unlock
Today	Unlock	Unlock	Unlock	Unlock

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: iperf3 3.22

Timelineinfo

09/28/2026 CVE reserved
09/30/2026 +2 days Advisory disclosed
09/30/2026 +0 days VulDB entry created
09/30/2026 +0 days VulDB entry last update

Sourcesinfo

Advisory: newreleases.io
Status: Confirmed

CVE: CVE-2026-101276 (🔒)
GCVE (CVE): GCVE-0-2026-101276
GCVE (VulDB): GCVE-100-412432

Entryinfo

Created: 09/30/2026 23:32
Changes: 09/30/2026 23:32 (67)
Complete: 🔍
Cache ID: 216::103