8 High
CVSS3
Attack Vector
ADJACENT
Attack Complexity
LOW
Privileges Required
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
0.001 Low
EPSS
Percentile
21.3%
Werkzeug multipart data parser needs to find a boundary that may be between consecutive chunks. That’s why parsing is based on looking for newline characters. Unfortunately, code looking for partial boundary in the buffer is written inefficiently, so if we upload a file that starts with CR or LF and then is followed by megabytes of data without these characters: all of these bytes are appended chunk by chunk into internal bytearray and lookup for boundary is performed on growing buffer.
This allows an attacker to cause a denial of service by sending crafted multipart data to an endpoint that will parse it. The amount of CPU time required can block worker processes from handling legitimate requests. The amount of RAM required can trigger an out of memory kill of the process. If many concurrent requests are sent continuously, this can exhaust or kill all available workers.
github.com/advisories/GHSA-hrfv-mqp8-q5rw
github.com/pallets/werkzeug/commit/b1916c0c083e0be1c9d887ee2f3d696922bfc5c1
github.com/pallets/werkzeug/commit/f2300208d5e2a5076cbbb4c2aad71096fd040ef9
github.com/pallets/werkzeug/commit/f3c803b3ade485a45f12b6d6617595350c0f03e2
github.com/pallets/werkzeug/security/advisories/GHSA-hrfv-mqp8-q5rw
github.com/pypa/advisory-database/tree/main/vulns/werkzeug/PYSEC-2023-221.yaml
nvd.nist.gov/vuln/detail/CVE-2023-46136
security.netapp.com/advisory/ntap-20231124-0008/