CVE-2021-27391

highpriority · track · 40EPSS 0.034 · 89 %ileDEEURUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
3.37% (89th) EPSS
CVSS 10 · high
Is it mine?
48 products
Check your exposure
Who says so?
5 sources
cnnvd · enisa_euvd · fstec_bdu · cisa_csaf_ot

EPSS · scored 2026-10-26

A vulnerability has been identified in APOGEE MBC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE MEC (PPC) (P2 Ethernet) (All versions >= V2.6.3), APOGEE PXC Compact (BACnet) (All versions < V3.5.3), APOGEE PXC Compact (P2 Ethernet) (All versions >= V2.8), APOGEE PXC Modular (BACnet) (All versions < V3.5.3), APOGEE PXC Modular (P2 Ethernet) (All versions >= V2.8), TALON TC Compact (BACnet) (All versions < V3.5.3), TALON TC Modular (BACnet) (All versions < V3.5.3). The web server of affected devices lacks proper bounds checking when parsing the Host parameter in HTTP requests, which could lead to a buffer overflow. An unauthenticated remote attacker could exploit this vulnerability to execute arbitrary code on the device with root privileges.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

A vendor fix is available.

  • FixedAPOGEE PXC Compact (BACnet)siemens_psirt

    Update to V3.5.3 or later version

  • FixedAPOGEE PXC Modular (BACnet)siemens_psirt

    Update to V3.5.3 or later version

  • FixedTALON TC Compact (BACnet)siemens_psirt

    Update to V3.5.3 or later version

  • FixedTALON TC Modular (BACnet)siemens_psirt

    Update to V3.5.3 or later version

  • FixedAPOGEE PXC Compact (BACnet)cisa_csaf_ot

    Update to V3.5.3 or later version

  • FixedAPOGEE PXC Modular (BACnet)cisa_csaf_ot

    Update to V3.5.3 or later version

  • FixedTALON TC Compact (BACnet)cisa_csaf_ot

    Update to V3.5.3 or later version

  • FixedTALON TC Modular (BACnet)cisa_csaf_ot

    Update to V3.5.3 or later version

  • MitigationAPOGEE MBC (PPC) (P2 Ethernet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE MEC (PPC) (P2 Ethernet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE PXC Compact (BACnet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE PXC Compact (P2 Ethernet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE PXC Modular (BACnet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE PXC Modular (P2 Ethernet)siemens_psirt

    Disable the integrated web server

  • MitigationTALON TC Compact (BACnet)siemens_psirt

    Disable the integrated web server

  • MitigationTALON TC Modular (BACnet)siemens_psirt

    Disable the integrated web server

  • MitigationAPOGEE MBC (PPC) (P2 Ethernet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationAPOGEE MEC (PPC) (P2 Ethernet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationAPOGEE PXC Compact (BACnet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationAPOGEE PXC Compact (P2 Ethernet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationAPOGEE PXC Modular (BACnet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationAPOGEE PXC Modular (P2 Ethernet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationTALON TC Compact (BACnet)cisa_csaf_ot

    Disable the integrated web server

  • MitigationTALON TC Modular (BACnet)cisa_csaf_ot

    Disable the integrated web server

  • No fix availableAPOGEE MBC (PPC) (P2 Ethernet)siemens_psirt

    Currently no remediation is available

  • No fix availableAPOGEE MEC (PPC) (P2 Ethernet)siemens_psirt

    Currently no remediation is available

  • No fix availableAPOGEE PXC Compact (P2 Ethernet)siemens_psirt

    Currently no remediation is available

  • No fix availableAPOGEE PXC Modular (P2 Ethernet)siemens_psirt

    Currently no remediation is available

  • No fix availableAPOGEE MBC (PPC) (P2 Ethernet)cisa_csaf_ot

    Currently no remediation is available

  • No fix availableAPOGEE MEC (PPC) (P2 Ethernet)cisa_csaf_ot

    Currently no remediation is available

  • No fix availableAPOGEE PXC Compact (P2 Ethernet)cisa_csaf_ot

    Currently no remediation is available

  • No fix availableAPOGEE PXC Modular (P2 Ethernet)cisa_csaf_ot

    Currently no remediation is available

02

cvss

Technical severity, 0–10. One row per scoring source.

10.0
010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · high–critical · 9–10

v2.010highAV:N/AC:L/Au:N/C:C/I:C/A:Cprimary · NVD / NIST USexploitability 10 · impact 10
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 5.9
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:T/RC:Csecondary · CISA US
v3.19.8criticalAV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · FSTEC (BDU) RU
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondary · ENISA EU
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:Hsecondaryexploitability 3.9 · impact 5.9
v3.19.8criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P/RL:T/RC:Csecondary · Siemens ProductCERT DE
v3.19criticalCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:Usecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: totalcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-119USCWE-120USCWE-120USCWE-120USCWE-120US
05

affected products (48)

Products and version ranges known to be affected.

showing 20 of 48
06

advisories (2)

Vendor and ecosystem advisories describing this.

  • SSA-944498SSA-944498: Buffer Overflow Vulnerability in Web Server of APOGEE and TALON Automation Devices2021-09-14csaf · siemens_psirtDE

    A buffer overflow vulnerability in the integrated web server of multiple APOGEE and TALON automation devices could allow a remote attacker to execute arbitrary code on the devices with root privileges. Affected devices include the APOGEE MBC/MEC/PXC P2 Ethernet devices with Power Open Processors (PPC), APOGEE PXC BACnet devices, and TALON TC BACnet devices. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends countermeasures for products where updates are not, or not yet available.

  • ICSA-21-257-07Siemens APOGEE and TALON2021-09-14icsa · cisa_csaf_otUS

    A buffer overflow vulnerability in the integrated web server of multiple APOGEE and TALON automation devices could allow a remote attacker to execute arbitrary code on the devices with root privileges. Affected devices include the APOGEE MBC/MEC/PXC P2 Ethernet devices with Power Open Processors (PPC), APOGEE PXC BACnet devices, and TALON TC BACnet devices. Siemens has released updates for several affected products and recommends to update to the latest versions. Siemens recommends countermeasures for products where updates are not, or not yet available.

07

also known as (4)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdfstec_bducisa_csaf_otsiemens_psirtNVDCVE.orgMITRE
published 2021-09-14modified 2026-06-17
09

references (7)

External citations — patches, advisories, analysis.

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