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Description
Gunicorn version 21.2.0 does not properly validate the value of the 'Transfer-Encoding' header as specified in the RFC standards, which leads to the default fallback method of 'Content-Length,' making it vulnerable to TE.CL request smuggling. This vulnerability can lead to cache poisoning, data exposure, session manipulation, SSRF, XSS, DoS, data integrity compromise, security bypass, information leakage, and business logic abuse.
Basic information
Type
reviewed
Severity
high Advisory on GitHub
Open advisory ↗ Repository advisory
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Source code
Browse source ↗ Published (advisory)
2025-03-20 12:32:45 UTC
Updated
2025-09-29 21:13:34 UTC
GitHub reviewed
2025-03-21 23:56:30 UTC
NVD published
2025-03-20
EPSS Score
Score
Percentile
0.07%
22.25%
CVSS Scores
Base score
Version
Severity
Vector
7.5
3.0
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CVSS:3.0/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.
CWEs
CWE id
Name
CWE-444
Inconsistent Interpretation of HTTP Requests ('HTTP Request/Response Smuggling')
Affected packages (1)
Vulnerable version ranges and first patched releases as published by GitHub.
Ecosystem
Package
Vulnerable range
First patched
Vulnerable functions
pip
gunicorn < 22.0.0
22.0.0
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cvelogic
Threat Intelligence