CVE-2018-16495Network attack vector

Session hijacking via unrotated authentication token

Published May 26, 2021 · Updated Aug 5, 2024

Session fixation in Versa Networks Versa Operating System allows remote attackers to hijack authenticated sessions via a preset token. The web interface issues an authentication token before login and retains that same token after successful authentication instead of rotating it. Exploitation requires a victim to authenticate through an attacker-prepared session; reuse of the known token grants the victim's application privileges.

CVSS severity8.8
High
EPSS probability0.91%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Session fixation in Versa Networks Versa Operating System allows remote attackers to hijack authenticated sessions via a preset token. The web interface issues an authentication token before login and retains that same token after successful authentication instead of rotating it. Exploitation requires a victim to authenticate through an attacker-prepared session; reuse of the known token grants the victim's application privileges.

The record

CVE
CVE-2018-16495
Published
May 26, 2021
Updated
Aug 5, 2024
Vendor
Versa Networks
Product
Versa Operating System (VOS)
Classifications
CWE-384, T1550.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 26, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 5, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=Fixed Versions: 16.1R2S11, 20.2.2, 21.1.1, 21.2.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Versa Networks · Versa Operating System (VOS)version=Fixed Versions: 16.1R2S11, 20.2.2, 21.1.1, 21.2.1

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-384Session Fixation
T1550.004Use Alternate Authentication Material: Web Session Cookie

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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