CVE-2020-25032: An issue was discovered in Flask-CORS (aka CORS Middleware for Flask) before 3.0.9.
Noroxi assessment
Priority: Monitor (action score 31/100)
- The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
- Probability of exploitation in the next 30 days: 3.9% (FIRST EPSS); higher than 90.3% of all records.
- Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
- Fixed version: python-flask-cors (Debian:10) 3.0.7-1+deb10u1; python-flask-cors (Debian:12) 3.0.9-1; python-Flask-Cors (openSUSE:Leap 15.1) 3.0.8-lp152.2.3.1.
Low priority for now. Upgrade to python-flask-cors (Debian:10) 3.0.7-1+deb10u1; python-flask-cors (Debian:12) 3.0.9-1; python-Flask-Cors (openSUSE:Leap 15.1) 3.0.8-lp152.2.3.1 or later.
Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it
Primary sources: NVD · CVE.org · FIRST EPSS
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.
- Published
- Aug 31, 2020
- Updated
- Jun 16, 2026
- EPSS
- 3.9% · 90th percentile
- CWE
- CWE-22
Report tools
Action score
31
Monitor
Low priority for now.
- CVSS
- 30 / 40 · 7.5 / 10
- CISA KEV
- 0 / 30 · Not listed
- EPSS
- 1 / 30 · 3.9%
Get told when this record changes
- Not in KEV: no record of exploitation in the wild
- No public exploit code on record
- A fix has been released
If any of these changes, we'll tell you in the daily email digest.
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Noroxi analysis
What does it mean in your environment?
The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.
We use this product, ask for helpAffected systems
Is your version affected?
Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.
| Vendor | Product | CPE |
|---|---|---|
| flask-cors project | flask-cors | cpe:2.3:a:flask-cors_project:flask-cors |
| debian | debian linux | cpe:2.3:o:debian:debian_linux |
| opensuse | backports sle | cpe:2.3:a:opensuse:backports_sle |
| opensuse | leap | cpe:2.3:o:opensuse:leap |
Affected versions
NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.
- debian debian linux10.0
- flask-cors project flask-corsbefore 3.0.9
- opensuse backports sle15.0
- opensuse leap15.1
- opensuse leap15.2
Package-level exposure
OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.
| Ecosystem | Package | Affected range | Fix |
|---|---|---|---|
| Debian:10 | python-flask-cors | before 3.0.7-1+deb10u1 | 3.0.7-1+deb10u1 |
| Debian:12 | python-flask-cors | before 3.0.9-1 | 3.0.9-1 |
| openSUSE:Leap 15.1 | python-Flask-Cors | before 3.0.8-lp152.2.3.1 | 3.0.8-lp152.2.3.1 |
| openSUSE:Tumbleweed | python-Flask-Cors | before 6.0.2-1.2 | 6.0.2-1.2 |
| openSUSE:Tumbleweed | python-Flask-Cors | before 4.0.0-1.3 | 4.0.0-1.3 |
| openSUSE:Tumbleweed | python-Flask-Cors | before 3.0.10-1.3 | 3.0.10-1.3 |
| PyPI | flask-cors | before 3.0.9 | 3.0.9 |
| SUSE:OpenStack Cloud 9 | ardana-ansible | before 9.0+git.1596813072.110811d-3.25.2 | 9.0+git.1596813072.110811d-3.25.2 |
| SUSE:OpenStack Cloud 9 | ardana-cinder | before 9.0+git.1596129576.0b3d3ce-3.13.2 | 9.0+git.1596129576.0b3d3ce-3.13.2 |
| SUSE:OpenStack Cloud 9 | ardana-cobbler | before 9.0+git.1588258487.3acf8ad-3.16.2 | 9.0+git.1588258487.3acf8ad-3.16.2 |
| SUSE:OpenStack Cloud 9 | ardana-installer-ui | before 9.0+git.1569535129.ca87ef0-3.13.2 | 9.0+git.1569535129.ca87ef0-3.13.2 |
| SUSE:OpenStack Cloud 9 | ardana-opsconsole-ui | before 9.0+git.1566593422.813e56c-4.13.2 | 9.0+git.1566593422.813e56c-4.13.2 |
| SUSE:OpenStack Cloud 9 | ardana-osconfig | before 9.0+git.1597427032.a062830-3.19.2 | 9.0+git.1597427032.a062830-3.19.2 |
| SUSE:OpenStack Cloud 9 | grafana | before 6.7.4-3.17.1 | 6.7.4-3.17.1 |
| SUSE:OpenStack Cloud 9 | grafana-natel-discrete-panel | before 0.0.9-4.3.3 | 0.0.9-4.3.3 |
| SUSE:OpenStack Cloud 9 | openstack-cinder | before 13.0.10~dev16-3.25.3 | 13.0.10~dev16-3.25.3 |
| SUSE:OpenStack Cloud 9 | openstack-dashboard | before 14.1.1~dev7-3.18.3 | 14.1.1~dev7-3.18.3 |
| SUSE:OpenStack Cloud 9 | openstack-ironic | before 11.1.5~dev16-3.22.3 | 11.1.5~dev16-3.22.3 |
| SUSE:OpenStack Cloud 9 | openstack-ironic-python-agent | before 3.3.4~dev5-3.16.2 | 3.3.4~dev5-3.16.2 |
| SUSE:OpenStack Cloud 9 | openstack-manila | before 7.4.2~dev54-4.27.3 | 7.4.2~dev54-4.27.3 |
| SUSE:OpenStack Cloud 9 | openstack-neutron | before 13.0.8~dev95-3.28.3 | 13.0.8~dev95-3.28.3 |
| SUSE:OpenStack Cloud 9 | openstack-nova | before 18.3.1~dev54-3.28.3 | 18.3.1~dev54-3.28.3 |
| SUSE:OpenStack Cloud 9 | python-Flask-Cors | before 3.0.3-4.3.2 | 3.0.3-4.3.2 |
| SUSE:OpenStack Cloud 9 | storm | before 1.2.3-3.3.4 | 1.2.3-3.3.4 |
+10
Same product
flask-cors project: all recordsOther highest-scoring records for the same primary product.
- CVE-2024-6866Case-Insensitive Path Matching in corydolphin/flask-cors30Monitor
- CVE-2024-6844Inconsistent CORS Matching Due to Handling of '+' in URL Path in corydolphin/flask-cors21Monitor
- CVE-2024-6839Improper Regex Path Matching in corydolphin/flask-cors21Monitor
Remediation
Which version to upgrade to
Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.
| Product / package | Fixed version | Source |
|---|---|---|
| debian:python-flask-cors | 3.0.9-1 · Debian:12 | Package registry (OSV) |
| opensuse:python-Flask-Cors | 3.0.8-lp152.2.3.1 · openSUSE:Leap 15.1 | Package registry (OSV) |
| PyPI:flask-cors | 3.0.9 | Package registry (OSV) |
| suse:ardana-ansible | 9.0+git.1596813072.110811d-3.25.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:ardana-cinder | 9.0+git.1596129576.0b3d3ce-3.13.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:ardana-cobbler | 9.0+git.1588258487.3acf8ad-3.16.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:ardana-installer-ui | 9.0+git.1569535129.ca87ef0-3.13.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:ardana-opsconsole-ui | 9.0+git.1566593422.813e56c-4.13.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:ardana-osconfig | 9.0+git.1597427032.a062830-3.19.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:grafana | 6.7.4-3.17.1 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:grafana-natel-discrete-panel | 0.0.9-4.3.3 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:openstack-cinder | 13.0.10~dev16-3.25.3 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:openstack-dashboard | 14.1.1~dev7-3.18.3 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:openstack-ironic | 11.1.5~dev16-3.22.3 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
| suse:openstack-ironic-python-agent | 3.3.4~dev5-3.16.2 · SUSE:OpenStack Cloud 9 | Package registry (OSV) |
Exploit status
No known public exploit
No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.
Research context
For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.
Timeline
From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.
No dated events beyond publication.
No history yet (it accumulates with the daily EPSS job).
Patch and commit links
Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.
No commit or PR link among the references.
Credits
All researchersFinders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.
No credits in the CNA record.
Variant candidates
Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.
No nightly-computed relations.
Chain candidates
An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.
—
Bug bounty scope
No known public program.
Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).
Technical details
Attack conditions
- Anyone who can reach it over the internet can trigger it.
- No account or password is required.
- No user action is required.
- No special conditions are required; it is repeatable.
If successful
- Confidentiality
- high · data can be read
- Integrity
- none
- Availability
- none
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality impact
- High
- Integrity impact
- None
- Availability impact
- None
Weakness class (CWE)
CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
nvd-primary
Root cause
A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.
The bug in code
The whole CWE-22 classA representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.
Vulnerable
const file = path.join(ROOT, req.query.name);
res.sendFile(file);Fixed
const file = path.resolve(ROOT, req.query.name);
if (!file.startsWith(ROOT + path.sep)) {
return res.sendStatus(400);
}
res.sendFile(file);Attack context
MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.
Attack patterns (CAPEC)
- Path TraversalCAPEC-126likelihood: High · Very High
- Using Slashes and URL Encoding Combined to Bypass Validation LogicCAPEC-64likelihood: High · High
- Manipulating Web Input to File System CallsCAPEC-76likelihood: High · Very High
- Using Escaped Slashes in Alternate EncodingCAPEC-78likelihood: High · High
- Using Slashes in Alternate EncodingCAPEC-79likelihood: High · High
ATT&CK techniques
—
Change log
- Fix✗ → ✓
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References
Show all references (5 more)Show less
Vendor advisories and official records. Exploit/PoC links are deliberately left out.