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CVE-2019-1010266: Regular Expression Denial of Service (ReDoS) in lodash

6.5

CVSS Score
3.1

Basic Information

EPSS Score
0.42047%
Published
7/19/2019
Updated
1/9/2023
KEV Status
No
Technology
TechnologyJavaScript

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
lodashnpm< 4.17.114.17.11
lodash-esnpm< 4.17.114.17.11
lodash-amdnpm< 4.17.114.17.11

Vulnerability Intelligence
Miggo AIMiggo AI

Miggo AIRoot Cause Analysis

The vulnerability was explicitly linked to the _.words implementation in the lodash changelog entry for 4.17.11. The commit 5c08f18 shows the regex pattern in reHasUnicodeWord was modified from /[A-Z]{2,}[a-z]/ to /[A-Z]{2}[a-z]/ to prevent excessive backtracking. The added performance test in test.js specifically validates _.words' handling of 50k-character strings, confirming this was the attack vector. The CVE description's reference to 'date handler' appears to be an error, as all technical evidence points to the words function and unicode word detection logic.

Vulnerable functions

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

WAF Protection Rules

WAF Rule

lo**s* prior to *.*.** is *****t** *y: *W*-***: Un*ontroll** R*sour** *onsumption. T** imp**t is: **ni*l o* s*rvi**. T** *ompon*nt is: **t* **n*l*r. T** *tt**k v**tor is: *tt**k*r provi**s v*ry lon* strin*s, w*i** t** li*r*ry *tt*mpts to m*t** usin*

Reasoning

T** vuln*r**ility w*s *xpli*itly link** to t** _.wor*s impl*m*nt*tion in t** lo**s* ***n**lo* *ntry *or *.**.**. T** *ommit ******* s*ows t** r***x p*tt*rn in r***sUni*o**Wor* w*s mo*i*i** *rom /[*-Z]{*,}[*-z]/ to /[*-Z]{*}[*-z]/ to pr*v*nt *x**ssiv*