CISA KEV High Cross-site scripting exploit reference

CVE-2019-18426 — WhatsApp Cross-Site Scripting Vulnerability

A vulnerability in WhatsApp Desktop versions prior to 0.3.9309 when paired with WhatsApp for iPhone versions prior to 2.20.10 allows cross-site scripting and local file reading. Exploiting the vulnerability requires the victim to click a link preview from a specially crafted text message.

Published Jan 21, 2020 · Updated Oct 13, 2026 · Sources: CISA Known Exploited Vulnerabilities, CVE Program (cve.org) e CISA ADP, NIST National Vulnerability Database · CNA: facebook

Urgent

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

CISA KEV · May 23, 2022 Exploit-DB · 1 Proofs of concept on GitHub · 1

How the score was calculated

Confirmed exploitation (CISA KEV)+35
Public exploit/PoC (exploitdb, github)+14
EPSS 67.9% (30-day exploitation probability)+15
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Confirmed

CISA KEV, listed May 23, 2022

EPSS FIRST

67.86%

ahead of 99% of scored CVEs · Oct 15, 2026

Affects

Facebook

WhatsApp Desktop and 1 more

CVSS base

8.2

High · 3 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

Active

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Partial

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

CISA required action CISA

Apply updates per vendor instructions.

US federal deadline: Jun 13, 2022 — passed 1586 day(s) ago

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Facebook WhatsApp Desktop, Whatsapp Whatsapp).
Treat as emergency remediation: the CVE is in CISA KEV (confirmed exploitation).
The attack is network-based and needs no privileges: restrict exposure (ACLs, VPN, WAF) until patched.
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Exploitation requires user interaction: tighten email/web filtering and warn affected users.
EPSS ahead of 99% of scored CVEs: prioritize it in the patch queue.
Search available logs for exploit probes matching the vulnerability class (cross-site scripting), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Facebook	WhatsApp Desktop	version 0.3.9309< 0.3.9309	Vulnerable	CVE Program (cve.org) e CISA ADP
Whatsapp	Whatsapp	< 0.3.9309< 2.20.10	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Network

Attack complexity

Low

Privileges required

None

User interaction

Required

Scope

Changed

Confidentiality

High

Integrity

Low

Availability

None

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.2	CVSS 3.1	High	2.8	4.7	nvd@nist.gov via NIST National Vulnerability Database
8.2	CVSS 3.1	High	2.8	4.7	134c704f-9b21-4f2e-91b3-4a467353bcc0 via NIST National Vulnerability Database
8.2	CVSS 3.1	High	—	—	CISA-ADP via CVE Program (cve.org) e CISA ADP
5.8	CVSS 2.0	Medium	8.6	4.9	nvd@nist.gov via NIST National Vulnerability Database

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N (score shown at the top: nvd@nist.gov)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-79 · Cross-site Scripting (XSS)

Other CVEs with this weakness →

CISA KEV details CISA

CISA lists a CVE once it has evidence of exploitation against real targets.

Listed

May 23, 2022

Federal deadline

Jun 13, 2022

passed 1586 day(s) ago

Ransomware use

Unknown

CISA records ransomware use only for campaigns it has confirmed, so “Unknown” means unrecorded, not ruled out. The deadline binds US federal agencies; for everyone else it is a reference date.

Public exploits, PoCs and detection templates

Public code that demonstrates or tests the flaw raises the odds of mass exploitation — and Nuclei templates help find vulnerable assets in your environment.

Exploit-DB

WhatsApp Desktop 0.3.9308 - Persistent Cross-Site Scripting Apr 6, 2020

Proofs of concept on GitHub

HumanSecurity/CVE-2019-18426 ★ 11 Feb 29, 2020

Warning: public PoCs are sometimes disguised malware. Use them only for authorized testing in an isolated environment. This portal does not host exploit code — it only points to the sources.

EPSS over time FIRST

Oct 13, 2026 → Oct 15, 2026 · 3 reading(s) · max 67.86%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Prioritize edge telemetry for the network-reachable component (proxy, WAF, IDS/IPS).
Monitor CSP violation reports and script payloads in reflected parameters.
Hunt retroactively in logs from before May 23, 2022 (KEV listing): exploitation may have started earlier.

web/proxy/WAF logsnetwork IDS/IPSapplication logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · whatsapp/whatsapp
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · Published → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record published
Oct 13, 2026
Affected products added · facebook/whatsapp desktop
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
CVSS changed · 8.2
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Source status changed · → Published
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Added to CISA KEV (detected)
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
Record created in this database
Oct 13, 2026 · CISA Known Exploited Vulnerabilities
2022
Added to CISA KEV catalog
May 22, 2022 · CISA
2020
CVE published
Jan 21, 2020 · facebook

Source activity

Repeated readings are counted rather than listed.

2× References added · Oct 13, 2026 – Oct 13, 2026
1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

3 on the record

www.facebook.com/security/advisories/cve-2019-18426
x_refsource_CONFIRM, Vendor Advisory, CVE Program (cve.org) e CISA ADP
www.cisa.gov/known-exploited-vulnerabilities-catalog
US Government Resource, NIST National Vulnerability Database
packetstormsecurity.com/files/157097/WhatsApp-Desktop-0.3.9308-Cross-Site-Scripting.html
x_refsource_MISC, Exploit, Third Party Advisory, VDB Entry, CVE Program (cve.org) e CISA ADP

Elsewhere on this site

Facebook
every CVE for this vendor

2022-05
what else CISA listed that month

Cross-site scripting
same class

CWE-79
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-23863 An attachment spoofing issue in WhatsApp for Windows prior to v2.3000.1032164386.258709… May 1, 2026
Medium CVE-2026-23866 Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for… May 1, 2026
Medium CVE-2025-55179 Incomplete validation of rich response messages in WhatsApp for iOS prior to… Nov 18, 2025
Medium CVE-2025-55177 Meta Platforms WhatsApp Incorrect Authorization Vulnerability KEV Aug 29, 2025
Critical CVE-2019-3568 WhatsApp VOIP Stack Buffer Overflow Vulnerability KEV May 14, 2019

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2019-18426 is "WhatsApp Cross-Site Scripting Vulnerability", rated High. It affects WhatsApp Desktop (Facebook); versions are in the scope table. It is in CISA KEV: there is evidence of real-world exploitation. CVSS 8.2 describes technical severity. EPSS 67.86% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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