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CVE-2020-1914

CVE-2020-1914: Always-Incorrect Control Flow Implementation in Facebook Hermes

9.8

CVSS Score
3.1

Basic Information

CVE ID
CVE-2020-1914
GHSA ID
GHSA-327c-qx3v-h673
EPSS Score
0.73865%
CWE
CWE-670
Published
5/24/2022
Updated
1/27/2023
KEV Status
No
Technology
TechnologyJavaScript

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
hermes-enginenpm<= 0.7.10.7.2

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability stemmed from improper instruction pointer handling in the interpreter loop for SaveGeneratorLong. The pre-patch code used a shared code path (doSaveGen) that set 'ip = NEXTINST(SaveGenerator)' regardless of whether the original instruction was SaveGenerator or SaveGeneratorLong. This failed to account for the longer instruction format, causing incorrect IP calculation. The patch specifically addresses this by using NEXTINST with the correct instruction type for each case.

Vulnerable functions

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

WAF Protection Rules

WAF Rule

* lo*i* vuln*r**ility w**n **n*lin* t** S*v***n*r*torLon* instru*tion in *****ook **rm*s prior to *ommit **************************************** *llows *tt**k*rs to pot*nti*lly r*** out o* *oun*s or t**or*ti**lly *x**ut* *r*itr*ry *o** vi* *r**t** J

Reasoning

T** vuln*r**ility st*mm** *rom improp*r instru*tion point*r **n*lin* in t** int*rpr*t*r loop *or `S*v***n*r*torLon*`. T** pr*-p*t** *o** us** * s**r** *o** p*t* (`*oS*v***n`) t**t s*t 'ip = N*XTINST(`S*v***n*r*tor`)' r***r*l*ss o* w**t**r t** ori*in*