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CVE-2018-7749

CVE-2018-7749: AsyncSSH SSH Server Authentication Bypass

9.8

CVSS Score
3.1

Basic Information

CVE ID
CVE-2018-7749
GHSA ID
GHSA-97cv-6pjf-5f9q
EPSS Score
0.6051%
CWE
CWE-287
Published
5/14/2022
Updated
9/4/2024
KEV Status
No
Technology
TechnologyPython

Technical Details

CVSS Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Package NameEcosystemVulnerable VersionsFirst Patched Version
AsyncSSHpip< 1.12.11.12.1

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stems from missing authentication state checks in the packet processing flow. The security fix in commit 16e6ebf adds a critical validation in _recv_packet() that rejects non-auth packets (types > MSG_USERAUTH_LAST) when auth_complete=False. The test case test_request_during_auth explicitly verifies this by attempting to send a global request during authentication. The vulnerable versions lacked this check, allowing packet processing to proceed before authentication completed.

Vulnerable functions

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

WAF Protection Rules

WAF Rule

T** SS* s*rv*r impl*m*nt*tion o* *syn*SS* ***or* *.**.* *o*s not prop*rly ****k w**t**r *ut**nti**tion is *ompl*t** ***or* pro**ssin* ot**r r*qu*sts. * *ustomiz** SS* *li*nt **n simply skip t** *ut**nti**tion st*p.

Reasoning

T** vuln*r**ility st*ms *rom missin* *ut**nti**tion st*t* ****ks in t** p**k*t pro**ssin* *low. T** s**urity *ix in *ommit ******* ***s * *riti**l v*li**tion in _r**v_p**k*t() t**t r*j**ts non-*ut* p**k*ts (typ*s > MS*_US*R*UT*_L*ST) w**n *ut*_*ompl*