CVE-2020-1920Public exploitNetwork attack vector

Application crash via exponential URL regex backtracking

Published Jun 1, 2021 · Updated Aug 4, 2024

ReDoS in Meta React Native 0.59.0 through 0.62.2 and 0.63.0 through 0.64.0 allows remote attackers to crash apps via a crafted URL. The validateBaseUrl function tests attacker-controlled URL text against an ambiguous hostname pattern whose overlapping repetitions trigger exponential backtracking. An application must construct React Native's URL object with attacker-controlled input; the affected regex is not called directly by the framework.

CVSS severity7.5
High
EPSS probability1.36%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

ReDoS in Meta React Native 0.59.0 through 0.62.2 and 0.63.0 through 0.64.0 allows remote attackers to crash apps via a crafted URL. The validateBaseUrl function tests attacker-controlled URL text against an ambiguous hostname pattern whose overlapping repetitions trigger exponential backtracking. An application must construct React Native's URL object with attacker-controlled input; the affected regex is not called directly by the framework.

The record

CVE
CVE-2020-1920
Published
Jun 1, 2021
Updated
Aug 4, 2024
Vendor
Meta
Product
React Native
Classifications
CWE-697, CWE-1333, T1642
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jun 1, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0.59.0 <unspecified

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Meta · React Nativeversion=0.59.0 <unspecified

Published CVSS scores

5.0NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-697Incorrect Comparison
CWE-1333Inefficient Regular Expression Complexity
T1642Endpoint Denial of Service

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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