CVE-2020-8476 [Medium] | Input Validation Bypass in 800xa System

For the Central Licensing Server component used in ABB products ABB Ability™ System 800xA and related system extensions versions 5.1, 6.0 and 6.1, Compact HMI versions 5.1 and 6.0, Control Builder Safe 1.0, 1.1 and 2.0, Symphony Plus -S+ Operations 3.0 to 3.2 Symphony Plus -S+ Engineering 1.1 to 2.2, Composer Harmony 5.1, 6.0 and 6.1, Melody Composer 5.3, 6.1/6.2 and SPE for Melody 1.0SPx (Composer 6.3), Harmony OPC Server (HAOPC) Standalone 6.0, 6.1 and 7.0, ABB Ability™ System 800xA/ Advant® OCS Control Builder A 1.3 and 1.4, Advant® OCS AC100 OPC Server 5.1, 6.0 and 6.1, Composer CTK 6.1 and 6.2, AdvaBuild 3.7 SP1 and SP2, OPCServer for MOD 300 (non-800xA) 1.4, OPC Data Link 2.1 and 2.2, Knowledge Manager 8.0, 9.0 and 9.1, Manufacturing Operations Management 1812 and 1909, ABB AbilityTM SCADAvantage versions 5.1 to 5.6.5, a weakness in validation of input exists that allows an attacker to alter licenses assigned to the system nodes by sending specially crafted messages to the CLS web service.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.26%	1.51%	+1.25%
2	2026-03-30	0.38%	0.26%	-0.12%
3	2025-11-21	—	0.38%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.26%

1.51%

+1.25%

2026-03-30

0.38%

0.26%

-0.12%

2025-11-21

—

0.38%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
5.3	3.1	MEDIUM	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:N) Data isn’t meaningfully altered or forged. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	3.9	1.4	[email protected]
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N` Click to expand Attack vector (AV:N) Could be attacked over the internet or any normal routed network—not just someone sitting at the machine. Attack complexity (AC:L) Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup. Privileges required (PR:N) No account or special rights needed—anonymous or random user is enough. User interaction (UI:N) Nobody has to click “OK” or open a trap file; it can work without a victim helping. Scope (S:U) Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems. Confidentiality (C:N) Doesn’t really leak secrets in a meaningful way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:N) Service keeps running; no real outage angle.	3.9	3.6	[email protected]
5.0	2.0	MEDIUM	`AV:N/AC:L/Au:N/C:N/I:P/A:N` Click to expand Access vector (AV:N) Can be exploited remotely over network reachability. Access complexity (AC:L) Exploitation conditions are straightforward and predictable. Authentication (AU:N) No authentication is required. Confidentiality impact (C:N) No confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:N) No availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

5.3

3.1

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

3.9

1.4

[email protected]

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N Click to expand

Attack vector (AV:N): Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L): Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N): No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N): Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U): Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:N): Doesn’t really leak secrets in a meaningful way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:N): Service keeps running; no real outage angle.

3.9

3.6

[email protected]

5.0

2.0

MEDIUM

AV:N/AC:L/Au:N/C:N/I:P/A:N Click to expand

Access vector (AV:N): Can be exploited remotely over network reachability.
Access complexity (AC:L): Exploitation conditions are straightforward and predictable.
Authentication (AU:N): No authentication is required.
Confidentiality impact (C:N): No confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:N): No availability impact.

10.0

2.9

[email protected]

Affected software / configurations for CVE-2020-8476

Vendor	Product	Version	Raw CPE
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:-::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:feature_pack_4::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:feature_pack_4_revision_d::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_a::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_b::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_c::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_d::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_e::::::
abb	800xa_system	5.1	cpe:2.3:a:abb:800xa_system:5.1:revision_e_feature_pack_4::::::
abb	800xa_system	6.0	cpe:2.3:a:abb:800xa_system:6.0:::::::*
abb	800xa_system	6.0.1	cpe:2.3:a:abb:800xa_system:6.0.1:::::::*
abb	800xa_system	6.0.3	cpe:2.3:a:abb:800xa_system:6.0.3:::::::*
abb	800xa_system	6.0.3.3	cpe:2.3:a:abb:800xa_system:6.0.3.3:::::::*
abb	800xa_system	6.1	cpe:2.3:a:abb:800xa_system:6.1:::::::*
abb	compact_hmi	5.1	cpe:2.3:a:abb:compact_hmi:5.1:-::::::
abb	compact_hmi	5.1	cpe:2.3:a:abb:compact_hmi:5.1:feature_pack_4_revision_d::::::
abb	compact_hmi	5.1	cpe:2.3:a:abb:compact_hmi:5.1:revision_b::::::
abb	compact_hmi	5.1	cpe:2.3:a:abb:compact_hmi:5.1:revision_d::::::
abb	compact_hmi	6.0.1-1	cpe:2.3:a:abb:compact_hmi:6.0.1-1:::::::*
abb	compact_hmi	6.0.3-2	cpe:2.3:a:abb:compact_hmi:6.0.3-2:::::::*
abb	control_builder_safe	1.0	cpe:2.3:a:abb:control_builder_safe:1.0:::::::*
abb	control_builder_safe	1.1	cpe:2.3:a:abb:control_builder_safe:1.1:::::::*
abb	control_builder_safe	2.0	cpe:2.3:a:abb:control_builder_safe:2.0:::::::*

References for CVE-2020-8476

URL	Tags
https://search.abb.com/library/Download.aspx?DocumentID=2PAA121230&LanguageCode=en&DocumentPartId=&Action=Launch	Vendor Advisory
https://search.abb.com/library/Download.aspx?DocumentID=2PAA121231&LanguageCode=en&DocumentPartId=&Action=Launch	Vendor Advisory
https://search.abb.com/library/Download.aspx?DocumentID=3CCA2020-003309&LanguageCode=en&DocumentPartId=&Action=Launch

URL

CVE-2020-8476 | ABB Central Licensing System - Elevation of Privilege Vulnerability

Exploit prediction scoring system (EPSS) score for CVE-2020-8476

Common vulnerability scoring system (CVSS) metrics for CVE-2020-8476

Weakness enumeration for CVE-2020-8476

Affected software / configurations for CVE-2020-8476

References for CVE-2020-8476