CVE-2023-3127 [High] | Authentication Bypass in Istar Ultra Firmware

CVE-2023-3127 is rated Moderate Risk (42.7/100): CVSS High severity, with low exploitation likelihood (EPSS 0.45%). Review affected assets and schedule remediation.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-06-15	0.17%	0.45%	+0.28%
2	2026-04-05	0.14%	0.17%	+0.03%
3	2025-11-21	—	0.14%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-06-15

0.17%

0.45%

+0.28%

2026-04-05

0.14%

0.17%

+0.03%

2025-11-21

—

0.14%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:L/I:H/A:L` Click to expand Attack vector (AV:A) Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet. Attack complexity (AC:H) Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work. 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:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. Confidentiality (C:L) Some sensitive info could get out, but not a total data dump. Integrity (I:H) They could widely tamper with or forge data—trust in the data is badly hurt. Availability (A:L) Might cause slowdowns, glitches, or partial disruption—not a full brick.	1.6	5.3	[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]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

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

Attack vector (AV:A): Attacker has to be nearby on the network—same office, same link, that vibe—not the whole wide internet.
Attack complexity (AC:H): Even with access, the exploit needs extra luck, timing, or a fussy environment to actually work.
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:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L): Some sensitive info could get out, but not a total data dump.
Integrity (I:H): They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:L): Might cause slowdowns, glitches, or partial disruption—not a full brick.

1.6

5.3

[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]

Affected software / configurations for CVE-2023-3127

Vendor	Product	Version	Raw CPE
johnsoncontrols	istar_ultra_firmware	>= 6.8.6, < 6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_firmware::::::::
johnsoncontrols	istar_ultra_firmware	6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_firmware:6.9.2:-::::::
johnsoncontrols	istar_ultra_lt_firmware	>= 6.8.6, < 6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_lt_firmware::::::::
johnsoncontrols	istar_ultra_lt_firmware	6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_lt_firmware:6.9.2:-::::::
johnsoncontrols	istar_ultra_g2_firmware	< 6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_g2_firmware::::::::
johnsoncontrols	istar_ultra_g2_firmware	6.9.2	cpe:2.3:o:johnsoncontrols:istar_ultra_g2_firmware:6.9.2:-::::::
johnsoncontrols	edge_g2_firmware	< 6.9.2	cpe:2.3:o:johnsoncontrols:edge_g2_firmware::::::::
johnsoncontrols	edge_g2_firmware	6.9.2	cpe:2.3:o:johnsoncontrols:edge_g2_firmware:6.9.2:-::::::

References for CVE-2023-3127

URL	Tags
https://www.cisa.gov/news-events/ics-advisories/icsa-23-192-02	Third Party Advisory US Government Resource
https://www.johnsoncontrols.com/cyber-solutions/security-advisories	Vendor Advisory

URL

CVE-2023-3127 | Improper Authentication in iSTAR

Exploit prediction scoring system (EPSS) score for CVE-2023-3127

Common vulnerability scoring system (CVSS) metrics for CVE-2023-3127

Weakness enumeration for CVE-2023-3127

Affected software / configurations for CVE-2023-3127

References for CVE-2023-3127