CVE-2021-34599Network attack vector

Repository interception and tampering via unvalidated certificates

Published Dec 1, 2021 · Updated Sep 17, 2024

Improper certificate validation in CODESYS Git before 1.1.0.0 allows man-in-the-middle attackers to read or alter Git traffic. Its HTTPS handshake accepts a server certificate without checking that it is valid and trusted, enabling interception or modification of repository exchanges. Exploitation requires control of the network path between the engineering workstation and its Git server; availability is not affected.

CVSS severity7.4
High
EPSS probability0.46%
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 CODESYS Git before 1.1.0.0 allows man-in-the-middle attackers to read or alter Git traffic. Its HTTPS handshake accepts a server certificate without checking that it is valid and trusted, enabling interception or modification of repository exchanges. Exploitation requires control of the network path between the engineering workstation and its Git server; availability is not affected.

The record

CVE
CVE-2021-34599
Published
Dec 1, 2021
Updated
Sep 17, 2024
Vendor
CODESYS GmbH
Product
CODESYS Git
Classifications
CWE-295, T1557
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Sep 17, 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=CODESYS Git <V1.1.0.0

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

CODESYS GmbH · CODESYS Gitversion=CODESYS Git <V1.1.0.0

Published CVSS scores

5.8NIST NVDAV:N/AC:M/Au:N/C:P/I:P/A:N
7.4CODESYS GmbHCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
7.4NIST NVDCVSS: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.

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-295Improper Certificate Validation
T1557Adversary-in-the-Middle

Public exploit references

No public exploit references are available in this record.

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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