CVE-2019-20374 [Critical]

A mutation cross-site scripting (XSS) issue in Typora through 0.9.9.31.2 on macOS and through 0.9.81 on Linux leads to Remote Code Execution through Mermaid code blocks. To exploit this vulnerability, one must open a file in Typora. The XSS vulnerability is then triggered due to improper HTML sanitization. Given that the application is based on the Electron framework, the XSS leads to remote code execution in an unsandboxed environment.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2025-11-21	1.21%	2.17%	+0.96%
2	2025-11-18	2.17%	1.21%	-0.96%
3	2025-04-28	—	2.17%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2025-11-21

1.21%

2.17%

+0.96%

2025-11-18

2.17%

1.21%

-0.96%

2025-04-28

—

2.17%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
9.6	3.1	CRITICAL	`CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. 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.	2.8	6.0	[email protected]
8.3	3.0	HIGH	`CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:C/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: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:R) A real person has to do something—click, install, enable—otherwise it doesn’t land. Scope (S:C) Breaking this can reach past the original component and bite other resources—bigger blast radius. 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.	1.6	6.0	[email protected]
6.8	2.0	MEDIUM	`AV:N/AC:M/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:M) Exploitation needs some favorable conditions, but not exceptional ones. 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.	8.6	6.4	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

9.6

3.1

CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/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:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.

2.8

6.0

[email protected]

8.3

3.0

HIGH

CVSS:3.0/AV:N/AC:H/PR:N/UI:R/S:C/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: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:R): A real person has to do something—click, install, enable—otherwise it doesn’t land.
Scope (S:C): Breaking this can reach past the original component and bite other resources—bigger blast radius.
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.

1.6

6.0

[email protected]

6.8

2.0

MEDIUM

AV:N/AC:M/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:M): Exploitation needs some favorable conditions, but not exceptional ones.
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.

8.6

6.4

[email protected]

Affected software / configurations for CVE-2019-20374

Vendor	Product	Version	Raw CPE
typora	typora	<= 0.9.81	cpe:2.3:a:typora:typora::::::::
typora	typora	<= 0.9.9.31.2	cpe:2.3:a:typora:typora::::::::

References for CVE-2019-20374

URL	Tags
https://github.com/cure53/DOMPurify/commit/4e8af7b2c4a159b683d317e02c5cbddb86dc4a0e	Patch Third Party Advisory
https://github.com/typora/typora-issues/issues/3124	Third Party Advisory

URL

CVE-2019-20374

Exploit prediction scoring system (EPSS) score for CVE-2019-20374

Common vulnerability scoring system (CVSS) metrics for CVE-2019-20374

Weakness enumeration for CVE-2019-20374

Affected software / configurations for CVE-2019-20374

References for CVE-2019-20374