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CVE-2021-40797

CVE-2021-40797: OpenStack Neutron Denial of Service vulnerability

6.5

CVSS Score
3.1

Basic Information

CVE ID
CVE-2021-40797
GHSA ID
GHSA-cpx3-696p-3cw9
EPSS Score
0.56361%
CWE
CWE-772
Published
5/24/2022
Updated
9/25/2024
KEV Status
No
Technology
TechnologyPython

Technical Details

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Package NameEcosystemVulnerable VersionsFirst Patched Version
neutronpip< 16.4.116.4.1
neutronpip>= 17.0.0, < 17.2.117.2.1
neutronpip>= 18.0.0, < 18.1.118.1.1

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stemmed from the use of routes.middleware.RoutesMiddleware with singleton=True in Neutron's API middleware stack. The commit e610a5eb9 explicitly fixes this by setting singleton=False. The singleton=True configuration caused thread-local storage (via _RequestConfig) to accumulate indefinitely when processing invalid API requests due to incompatibility with eventlet's monkeypatched threading.local implementation. This matches the CWE-772 (resource retention) description and the patch's focus on this parameter change.

Vulnerable functions

Only Mi**o us*rs **n s** t*is s**tion

WAF Protection Rules

WAF Rule

*n issu* w*s *is*ov*r** in t** rout*s mi**l*w*r* in Op*nSt**k N*utron ***or* **.*.*, **.x ***or* **.*.*, *n* **.x ***or* **.*.*. *y m*kin* *PI r*qu*sts involvin* non*xist*nt *ontroll*rs, *n *ut**nti**t** us*r m*y **us* t** *PI work*r to *onsum* in*r*

Reasoning

T** vuln*r**ility st*mm** *rom t** us* o* `rout*s.mi**l*w*r*.Rout*sMi**l*w*r*` wit* sin*l*ton=Tru* in N*utron's *PI mi**l*w*r* st**k. T** *ommit ********* *xpli*itly *ix*s t*is *y s*ttin* sin*l*ton=**ls*. T** sin*l*ton=Tru* *on*i*ur*tion **us** t*r**