VDB-318716 · CVE-2025-8556 · Nessus 281820

Cloudflare CIRCL 1.6.0 Session signature verification

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.
4.5	$0-$5k	0.00

Summaryinfo

A vulnerability was found in Cloudflare CIRCL 1.6.0. It has been declared as problematic. This affects an unknown part of the component Session Handler. Such manipulation leads to an unknown weakness. This vulnerability is documented as CVE-2025-8556. There is not any exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Cloudflare CIRCL 1.6.0. It has been rated as problematic. Affected by this issue is some unknown processing of the component Session Handler. Using CWE to declare the problem leads to CWE-347. The product does not verify, or incorrectly verifies, the cryptographic signature for data. The impact remains unknown. CVE summarizes:

A flaw was found in CIRCL's implementation of the FourQ elliptic curve. This vulnerability allows an attacker to compromise session security via low-order point injection and incorrect point validation during Diffie-Hellman key exchange.

The advisory is shared for download at bugzilla.redhat.com. This vulnerability is handled as CVE-2025-8556. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 281820 (Amazon Linux 2 : amazon-ssm-agent, --advisory ALAS2-2025-3121 (ALAS-2025-3121)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 1.6.1 eliminates this vulnerability. The upgrade is hosted for download at github.com.

The vulnerability is also documented in the vulnerability database at Tenable (281820). Once again VulDB remains the best source for vulnerability data.

Productinfo

Type

Cloud Software

Vendor

Cloudflare

Name

CIRCL

Version

1.6.0

CPE 2.3info

🔒

CPE 2.2info

🔒

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 4.6
VulDB Meta Temp Score: 4.5

VulDB Base Score: 5.5
VulDB Temp Score: 5.3
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 3.7
CNA Vector: 🔒

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: Signature verification
CWE: CWE-347 / CWE-345
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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

Nessus ID: 281820
Nessus Name: Amazon Linux 2 : amazon-ssm-agent, --advisory ALAS2-2025-3121 (ALAS-2025-3121)

Threat Intelligenceinfo

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

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: CIRCL 1.6.1

Timelineinfo

08/04/2025 Advisory disclosed
08/04/2025 +0 days VulDB entry created
01/06/2026 +155 days VulDB entry last update

Sourcesinfo

Advisory: bugzilla.redhat.com
Status: Confirmed

CVE: CVE-2025-8556 (🔒)
GCVE (CVE): GCVE-0-2025-8556
GCVE (VulDB): GCVE-100-318716

Entryinfo

Created: 08/04/2025 21:48
Updated: 01/06/2026 12:31
Changes: 08/04/2025 21:48 (52), 08/06/2025 11:33 (14), 10/23/2025 05:26 (1), 01/06/2026 12:31 (2)
Complete: 🔍
Cache ID: 216::103