CVE-2020-24683 [Critical] | Authentication Bypass in Symphony \+ Historian

The affected versions of S+ Operations (version 2.1 SP1 and earlier) used an approach for user authentication which relies on validation at the client node (client-side authentication). This is not as secure as having the server validate a client application before allowing a connection. Therefore, if the network communication or endpoints for these applications are not protected, unauthorized actors can bypass authentication and make unauthorized connections to the server application.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.45%	1.41%	+0.96%
2	2025-03-30	0.88%	0.45%	-0.43%
3	2025-03-29	—	0.88%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.45%

1.41%

+0.96%

2025-03-30

0.88%

0.45%

-0.43%

2025-03-29

—

0.88%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` 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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
9.8	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H` 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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:H) Could take the service down hard or make it unusable for people who depend on it.	3.9	5.9	[email protected]
7.5	2.0	HIGH	`AV:N/AC:L/Au:N/C:P/I:P/A:P` 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:P) Partial confidentiality impact. Integrity impact (I:P) Partial integrity impact. Availability impact (A:P) Partial availability impact.	10.0	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

9.8

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H 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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H): Could take the service down hard or make it unusable for people who depend on it.

3.9

5.9

[email protected]

7.5

2.0

HIGH

AV:N/AC:L/Au:N/C:P/I:P/A:P 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:P): Partial confidentiality impact.
Integrity impact (I:P): Partial integrity impact.
Availability impact (A:P): Partial availability impact.

10.0

6.4

[email protected]

Weakness enumeration for CVE-2020-24683

Affected software / configurations for CVE-2020-24683

Vendor	Product	Version	Raw CPE
abb	symphony_\+_historian	3.0	cpe:2.3:a:abb:symphony_\+_historian:3.0:::::::*
abb	symphony_\+_historian	3.1	cpe:2.3:a:abb:symphony_\+_historian:3.1:::::::*
abb	symphony_\+_operations	1.1	cpe:2.3:a:abb:symphony_\+_operations:1.1:::::::*
abb	symphony_\+_operations	2.0	cpe:2.3:a:abb:symphony_\+_operations:2.0:::::::*
abb	symphony_\+_operations	2.1	cpe:2.3:a:abb:symphony_\+_operations:2.1:sp1::::::
abb	symphony_\+_operations	2.1	cpe:2.3:a:abb:symphony_\+_operations:2.1:sp2::::::
abb	symphony_\+_operations	3.0	cpe:2.3:a:abb:symphony_\+_operations:3.0:::::::*
abb	symphony_\+_operations	3.1	cpe:2.3:a:abb:symphony_\+_operations:3.1:::::::*
abb	symphony_\+_operations	3.2	cpe:2.3:a:abb:symphony_\+_operations:3.2:::::::*
abb	symphony_\+_operations	3.3	cpe:2.3:a:abb:symphony_\+_operations:3.3:::::::*

References for CVE-2020-24683

URL	Tags
https://search.abb.com/library/Download.aspx?DocumentID=2PAA123980&LanguageCode=en&DocumentPartId=&Action=Launch	Mitigation Vendor Advisory

URL

CVE-2020-24683 | Authentication Bypass in Symphony Plus

Exploit prediction scoring system (EPSS) score for CVE-2020-24683

Common vulnerability scoring system (CVSS) metrics for CVE-2020-24683

Weakness enumeration for CVE-2020-24683

Affected software / configurations for CVE-2020-24683

References for CVE-2020-24683