CVE-2020-25032 [High] | Path Traversal in Flask-Cors

An issue was discovered in Flask-CORS (aka CORS Middleware for Flask) before 3.0.9. It allows ../ directory traversal to access private resources because resource matching does not ensure that pathnames are in a canonical format.

#	Date	Old EPSS score	New EPSS score	Delta (New - Old)
1	2026-04-15	0.73%	0.90%	+0.16%
2	2026-03-04	0.27%	0.73%	+0.46%
3	2026-03-01	—	0.27%	—

Date

Old EPSS score

New EPSS score

Delta (New - Old)

2026-04-15

0.73%

0.90%

+0.16%

2026-03-04

0.27%

0.73%

+0.46%

2026-03-01

—

0.27%

—

Base score	Version	Severity	Vector	Exploitability	Impact	Score source
7.5	3.1	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:H) Serious risk that confidential data gets exposed in a big way. Integrity (I:N) Data isn’t meaningfully altered or forged. 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:P/I:N/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:P) Partial confidentiality impact. Integrity impact (I:N) No integrity impact. Availability impact (A:N) No availability impact.	10.0	2.9	[email protected]

Base score

Version

Severity

Vector

Exploitability

Impact

Score source

7.5

3.1

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/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:H): Serious risk that confidential data gets exposed in a big way.
Integrity (I:N): Data isn’t meaningfully altered or forged.
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:P/I:N/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:P): Partial confidentiality impact.
Integrity impact (I:N): No integrity impact.
Availability impact (A:N): No availability impact.

10.0

2.9

[email protected]

OS Trackers for CVE-2020-25032

vendor	priority	summary	link
`debian`	not yet assigned	CVE-2020-25032 not yet assigned priority: Debian including 1 source packages (python-flask-cors), 5 status rows across 5 suites (bookworm, bullseye, forky, sid, trixie): resolved 5.	https://security-tracker.debian.org/tracker/CVE-2020-25032
`redhat`	medium	—	https://access.redhat.com/security/cve/CVE-2020-25032
`suse`	medium	CVE-2020-25032 severity moderate: SUSE including 179 source package names (ansible-2.9.14-3.15.1, ardana-ansible-8.0+git.1596735237.54109b1-3.77.1, …), 355 product×package rows across 10 product lines (HPE Helion OpenStack 8, SUSE OpenStack Cloud 8, … (10 product lines)): Fixed 355.	https://www.suse.com/security/cve/CVE-2020-25032/
`ubuntu`	medium	CVE-2020-25032 medium priority: Ubuntu including 1 source packages (python-flask-cors), 11 status rows across 11 suites (bionic, focal, groovy, hirsute, impish, jammy, kinetic, lunar, trusty, upstream, xenial): not-affected 5, DNE 3, released 2, ignored 1.	https://ubuntu.com/security/CVE-2020-25032

Affected software / configurations for CVE-2020-25032

Vendor	Product	Version	Raw CPE
flask-cors_project	flask-cors	< 3.0.9	cpe:2.3:a:flask-cors_project:flask-cors::::::::
debian	debian_linux	10.0	cpe:2.3:o:debian:debian_linux:10.0:::::::*
opensuse	backports_sle	15.0	cpe:2.3:a:opensuse:backports_sle:15.0:sp1::::::
opensuse	backports_sle	15.0	cpe:2.3:a:opensuse:backports_sle:15.0:sp2::::::
opensuse	leap	15.1	cpe:2.3:o:opensuse:leap:15.1:::::::*
opensuse	leap	15.2	cpe:2.3:o:opensuse:leap:15.2:::::::*

References for CVE-2020-25032

URL	Tags
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00028.html	Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00032.html	Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00039.html	Mailing List Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-09/msg00048.html	Mailing List Third Party Advisory
https://github.com/corydolphin/flask-cors/releases/tag/3.0.9	Third Party Advisory
https://www.debian.org/security/2020/dsa-4775	Third Party Advisory

URL

CVE-2020-25032

Exploit prediction scoring system (EPSS) score for CVE-2020-25032

Common vulnerability scoring system (CVSS) metrics for CVE-2020-25032

Weakness enumeration for CVE-2020-25032

GitHub Security Advisory for CVE-2020-25032

OS Trackers for CVE-2020-25032

Affected software / configurations for CVE-2020-25032

References for CVE-2020-25032