Avantra: Unprotected Transport of Credentials
CVE-2026-8673 is a critical-severity unprotected transport of credentials vulnerability in Avantra from Syslink Software, with a CVSS 3.1 base score of 9.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 25.3.0 as the first without the flaw, so updating Avantra to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.19% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Update Avantra to 25.3.0 or a later version.
- Read the advisory on support.avantra.com for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Syslink Software | Avantra | before 25.3.0 | 25.3.0 |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- UnchangedImpact stays within the vulnerable component.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- NoneAvailability is not affected.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 5.9 | Medium | CNA (ncsc.ch) |
| CVSS 3.1 | 9.1 | Critical | NVD |
Official description
Unprotected transport of credentials vulnerability in syslink software AG Avantra on Linux, Windows allows Sniffing Attacks. This issue affects Avantra: before 25.3.0.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Unprotected Transport of Credentials
Login pages do not use adequate measures to protect the user name and password while they are in transit from the client to the server.
More Unprotected Transport of Credentials vulnerabilities (CWE-523)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in Avantra
- 7.5 High severity
- 9.6 Critical severity
- 7.2 High severity
Recent Unprotected Transport of Credentials vulnerabilities
- 7.4 High severity
- 8.8 High severity
- 9.1 Critical severity
- 7.1 High severity
- 7.3 High severity
- 7.5 High severity
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