CVE-2021-36369
highpriority · track · 31EPSS 0.019 · 79 %ileDEEURUUSEPSS · scored 2026-10-22
An issue was discovered in Dropbear through 2020.81. Due to a non-RFC-compliant check of the available authentication methods in the client-side SSH code, it is possible for an SSH server to change the login process in its favor. This attack can bypass additional security measures such as FIDO2 tokens or SSH-Askpass. Thus, it allows an attacker to abuse a forwarded agent for logging on to another server unnoticed.
remediations
Vendor fix, mitigation, or workaround guidance, as published by each source.
A vendor fix is available.
- FixedSCALANCE XCH328 (6GK5328-4TS01-2EC2)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM324 (6GK5324-8TS01-2AC2)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM328 (6GK5328-4TS01-2AC2)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM332 (6GK5332-0GA01-2AC2)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRH334 (24 V DC, 8xFO, CC) (6GK5334-2TS01-2ER3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (230 V AC, 12xFO) (6GK5334-3TS01-3AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (230 V AC, 8xFO) (6GK5334-2TS01-3AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (24 V DC, 12xFO) (6GK5334-3TS01-2AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (24 V DC, 8xFO) (6GK5334-2TS01-2AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (2x230 V AC, 12xFO) (6GK5334-3TS01-4AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (2x230 V AC, 8xFO) (6GK5334-2TS01-4AR3)siemens_psirt
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCH328 (6GK5328-4TS01-2EC2)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM324 (6GK5324-8TS01-2AC2)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM328 (6GK5328-4TS01-2AC2)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XCM332 (6GK5332-0GA01-2AC2)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRH334 (24 V DC, 8xFO, CC) (6GK5334-2TS01-2ER3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (230 V AC, 12xFO) (6GK5334-3TS01-3AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (230 V AC, 8xFO) (6GK5334-2TS01-3AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (24 V DC, 12xFO) (6GK5334-3TS01-2AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (24 V DC, 8xFO) (6GK5334-2TS01-2AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (2x230 V AC, 12xFO) (6GK5334-3TS01-4AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/ - FixedSCALANCE XRM334 (2x230 V AC, 8xFO) (6GK5334-2TS01-4AR3)cisa_csaf_ot
Update to V2.4 or later version
https://support.industry.siemens.com/cs/ww/en/view/109826613/
cvss
Technical severity, 0–10. One row per scoring source.
base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · medium–high · 6.9–7.5
ssvc
A stakeholder decision — act, attend, or track — from exploitation and impact.
weaknesses
The CWE weakness classes this flaw belongs to.
affected products (37)
Products and version ranges known to be affected.
advisories (2)
Vendor and ecosystem advisories describing this.
- SSA-806742SSA-806742: Multiple Vulnerabilities in SCALANCE XCM-/XRM-300 before V2.42024-02-13csaf · siemens_psirtDE
SCALANCE XCM-/XRM-300 before V2.4 is affected by multiple vulnerabilities. Siemens has released an update for SCALANCE X-300 and recommends to update to the latest version.
- ICSA-24-046-11Siemens SCALANCE XCM-/XRM-3002024-02-13icsa · cisa_csaf_otUS
SCALANCE XCM-/XRM-300 before V2.4 is affected by multiple vulnerabilities. Siemens has released an update for SCALANCE X-300 and recommends to update to the latest version.
also known as (4)
Other names and identifiers for this entity.
sources
Which sources assert this record, and when.
references (15)
External citations — patches, advisories, analysis.
- https://cxsecurity.com/cveshow/CVE-2021-36369/cnnvd
- https://github.com/mkj/dropbear/Patchcnnvd
- https://github.com/mkj/dropbear/pull/128cnnvd
- https://github.com/mkj/dropbear/releases/tag/DROPBEAR_2022.82cnnvd
- https://lists.debian.org/debian-lts-announce/2022/11/msg00015.htmlcnnvd
- https://vigilance.fr/vulnerability/Dropbear-Man-in-the-Middle-via-Login-Process-39903cnnvd
- https://www.auscert.org.au/bulletins/ESB-2022.5862cnnvd
- https://github.com/mkj/dropbear/pull/128enisa_euvd
Attackers weaponise vulnerabilities like this against internet-exposed services. See what is exposed on your perimeter with a free passive scan.
Free scan