Trending
CVE-2026-27199

CVE detail

CVE-2026-27199

Werkzeug is a comprehensive WSGI web application library. Versions 3.1.5 and below, the safe_join function allows Windows device names as filenames if preceded by other path segments. This was previously reported as GHSA-hgf8-39gv-g3f2, but the added filtering failed to account for the fact that safe_join accepts paths with multiple segments, such as example/NUL. The function send_from_directory uses safe_join to safely serve files at user-specified paths under a directory. If the application is running on Windows, and the requested path ends with a special device name, the file will be opened successfully, but reading will hang indefinitely. This issue has been fixed in version 3.1.6.

CVSS 6.3 · MediumBuzz score 18.9

Buzz score

Why this CVE is surfacing

Buzz score total 18.9

This all-time snapshot uses the same composite formula as Trending across a 30-year evidence window, rather than a current rolling window.

Buzz score components · mention 13.9 · diversity 5.0 · KEV 0.0 · OTX 0.0 · PoC 0.0

Mention score

13.9

3 evidence mentions in the snapshot

Diversity score

5.0

1 sources across 1 categories

KEV score

0.0

No KEV entry observed

OTX score

0.0

0 OTX pulses

PoC score

0.0

0 repos · best confidence N/A

Best PoC traction

Maximum stars on a matched PoC repo

Why it matters now

Mention timeline

Total mentions: 0; within the 30d window
Peak daily: 0; highest bucket

Evidence

Source links by recency

Newest mentions first

3 source links · newest first

https://github.com/pallets/werkzeug/security/advisories/GHSA-29vq-49wr-vm6xgithub.com
No excerpt available.
Exploitgithub.comFeb 21, 2026, 6:17 AM
https://github.com/pallets/werkzeug/releases/tag/3.1.6github.com
No excerpt available.
Exploitgithub.comFeb 21, 2026, 6:17 AM
https://github.com/pallets/werkzeug/commit/f407712fdc60a09c2b3f4fe7db557703e5d9338dgithub.com
No excerpt available.
Exploitgithub.comFeb 21, 2026, 6:17 AM

Exploit code

Public exploit repository references

Public PoC repositories are third-party, potentially unsafe artifacts. Treat their code as untrusted and use it only on authorized systems in an isolated, least-privilege environment. cvebuzz does not execute the code or verify that an exploit works.

0 repository references · best confidence N/A · max 0 stars

No public PoC repositories have been matched yet.

Related records

Similar CVEs

6 related CVEs with shared weakness or product evidence

CVE-2026-21860
Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.5, Werkzeug's safe_join function allows path segments with Windows device names that have file exten…
CVSS 6.3 · Medium
2 mentions
CVE-2025-66221
Werkzeug is a comprehensive WSGI web application library. Prior to version 3.1.4, Werkzeug's safe_join function allows path segments with Windows device names. On Windows, there a…
CVSS 6.3 · Medium
CVE-2024-51745
Wasmtime is a fast and secure runtime for WebAssembly. Wasmtime's filesystem sandbox implementation on Windows blocks access to special device filenames such as "COM1", "COM2", "L…
CVSS 2.3 · Low
CVE-2024-35197
gitoxide is a pure Rust implementation of Git. On Windows, fetching refs that clash with legacy device names reads from the devices, and checking out paths that clash with such na…
CVSS 5.4 · Medium
CVE-2024-49767
Werkzeug is a Web Server Gateway Interface web application library. Applications using `werkzeug.formparser.MultiPartParser` corresponding to a version of Werkzeug prior to 3.0.6…
CVSS 6.9 · Medium
CVE-2024-49766
Werkzeug is a Web Server Gateway Interface web application library. On Python < 3.11 on Windows, os.path.isabs() does not catch UNC paths like //server/share. Werkzeug's safe_join…
CVSS 6.3 · Medium

External lookup

Potential internet exposure

Potential exposure only — not proof of vulnerability.Shodan results indicate potentially internet-exposed products, not confirmed vulnerable systems. They do not confirm that any returned system is vulnerable to CVE-2026-27199.

Product-level CPE searches intentionally omit version fields and NVD version-range or configuration certainty. Verify the exact product version and configuration independently.

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Product CPE queries

Derived from this CVE's existing NVD CPE 2.3 records; the application, operating-system, or hardware part is retained.

cpe:2.3:a:palletsprojects:werkzeugSearch this product on Shodan

Exact CVE query

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Metadata

Canonical fields

NVD status

Analyzed

Published

Feb 21, 2026

Modified

Jun 17, 2026

Official record

Authoritative NVD record

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

CWE IDs

Vendor classifications

How this vector reads

CVSS 4.0 base metrics decoded below. This explanation does not recalculate or change the NVD score.

Attack Vector (AV): Network. The vulnerable system can be reached across network boundaries.
Attack Complexity (AC): Low. No special conditions beyond the attacker-controlled steps are required.
Attack Requirements (AT): Present. A prerequisite deployment or execution condition must be present.
Privileges Required (PR): None. The attacker needs no privileges on the vulnerable system.
User Interaction (UI): None. Exploitation does not require a targeted user to act.
Vulnerable System Confidentiality (VC): None. There is no direct impact to this security property.
Vulnerable System Integrity (VI): None. There is no direct impact to this security property.
Vulnerable System Availability (VA): Low. There is a limited impact to this security property.
Subsequent System Confidentiality (SC): None. There is no direct impact to this security property.
Subsequent System Integrity (SI): None. There is no direct impact to this security property.
Subsequent System Availability (SA): None. There is no direct impact to this security property.

Optional CVSS v4 metrics remain in the raw vector; only base metrics are expanded here.

Signals

Exploitation indicators

0 stored signals · no KEV · 0 OTX pulses