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CVE-2021-32633: Remote Code Execution via traversal in TAL expressions

6.8

CVSS Score
3.1

Basic Information

EPSS Score
0.7528%
Published
6/18/2021
Updated
11/19/2024
KEV Status
No
Technology
TechnologyPython

Technical Details

CVSS Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
Package NameEcosystemVulnerable VersionsFirst Patched Version
Zopepip< 4.64.6
Zopepip>= 5.0, < 5.25.2

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stems from insufficient validation of path traversal in TAL expressions. The commit patches show both functions lacked checks for names starting with underscores, which allowed attackers to traverse into protected attributes/modules. The added checks for 'name.startswith('_')' in both functions confirm these were the entry points for unsafe traversal. Exploit examples (e.g., 'random/_os/system') and CWE-22 classification further validate the path traversal mechanism as the root cause.

Vulnerable functions

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

WAF Protection Rules

WAF Rule

### Imp**t Most Pyt*on mo*ul*s *r* not *v*il**l* *or usin* in T*L *xpr*ssions t**t you **n *** t*rou**-t**-w**, *or *x*mpl* in Zop* P*** T*mpl*t*s. T*is r*stri*tion *voi*s *il* syst*m ****ss, *or *x*mpl* vi* t** 'os' mo*ul*. *ut som* o* t** untrust**

Reasoning

T** vuln*r**ility st*ms *rom insu**i*i*nt v*li**tion o* p*t* tr*v*rs*l in T*L *xpr*ssions. T** *ommit p*t***s s*ow *ot* *un*tions l**k** ****ks *or n*m*s st*rtin* wit* un**rs*or*s, w*i** *llow** *tt**k*rs to tr*v*rs* into prot**t** *ttri*ut*s/mo*ul*s