CVE-2023-6680Public exploitNetwork attack vector

Account impersonation via unbound certificate parameter

Published Dec 15, 2023 · Updated Jun 6, 2026

Improper certificate validation in affected GitLab EE versions allows remote attackers to impersonate Smartcard users. The /-/smartcard/verify_certificate endpoint accepted a plaintext client_certificate parameter without binding it to the preceding TLS proof of private-key possession. Exposure requires an administrator to enable the experimental Smartcard feature; affected releases are 11.6 through 16.4.3, 16.5 through 16.5.3, and 16.6 through 16.6.1.

CVSS severity7.4
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper certificate validation in affected GitLab EE versions allows remote attackers to impersonate Smartcard users. The /-/smartcard/verify_certificate endpoint accepted a plaintext client_certificate parameter without binding it to the preceding TLS proof of private-key possession. Exposure requires an administrator to enable the experimental Smartcard feature; affected releases are 11.6 through 16.4.3, 16.5 through 16.5.3, and 16.6 through 16.6.1.

The record

CVE
CVE-2023-6680
Published
Dec 15, 2023
Updated
Jun 6, 2026
Vendor
GitLab
Product
GitLab
Classifications
CWE-295, T1078
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 15, 2023CVE publishedPublication date reported by the CVE source.
  2. Jun 6, 2026Record 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=11.6 <16.4.4
  2. Affected versionversion=16.5 <16.5.4
  3. Affected versionversion=16.6 <16.6.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

GitLab · GitLabversion=11.6 <16.4.4; version=16.5 <16.5.4; version=16.6 <16.6.2

Published CVSS scores

8.1NIST NVDCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
7.4GitLab Inc.CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N

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.

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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 exploitPublished

Weakness, pattern, technique

CWE-295Improper Certificate Validation
T1078Valid Accounts

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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