WhatsApp VOIP Stack Buffer Overflow Vulnerability (CVE-2019-3568)
Published In CISA KEV since Sources: CVE.org
What is affected, what to do
A buffer overflow vulnerability in WhatsApp VOIP stack allowed remote code execution via specially crafted series of RTCP packets sent to a target phone number. The issue affects WhatsApp for Android prior to v2.19.134, WhatsApp Business for Android prior to v2.19.44, WhatsApp for iOS prior to v2.19.51, WhatsApp Business for iOS prior to v2.19.51, WhatsApp for Windows Phone prior to v2.18.348, and WhatsApp for Tizen prior to v2.18.15.
The vulnerability is being actively exploited; treat it as a priority. The available sources name no fixed version. Check the vendor guidance in the references below. Immediate actions, mitigation and detection rules are in the runbook below.
Conflicting version data — version display is hidden until the data is resolved.
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Metrics
9.8
Priority
XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.
Source: NVD, CVSS v3
9.8
CVSS v3
Severity Critical on the scale from 0 to 10.
Source: CVE.org
30.1 %
EPSS score
Elevated — model estimates 10-50% exploitation likelihood.
Source: FIRST EPSS, percentile 98.2
Show all metrics
- Severity
- Critical
Priority (0–325)
The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?
Read in glossary- 226.18 Methodology
Exploit maturity
An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.
Read in glossary- actively exploited
XIEM Effective CVSS
XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.
Read in glossary- 9.8 Methodology
CVSS v3
CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.
Read in glossary- 9.8
EPSS score
The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.
Read in glossary- 30.1 %
- Elevated — model estimates 10-50% exploitation likelihood.
EPSS percentile
The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.
Read in glossary- 98.2
- Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
KEV status
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- Actively exploited
- Published
In CISA KEV since
The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.
Read in glossary- CISA assessment (SSVC)
- Exploitation: active · automatable · Technical impact: total
- Source: CISA Vulnrichment, as of 7 February 2025
CWE
CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.
Read in glossary- CWE-122
Response and mitigation
Why act now?
Prioritisation rationale
This flaw is network-reachable without authentication or any user interaction: a crafted call is enough, and it does not need to be answered. Exploitation likelihood is rated very high. In practice it was used to deliver targeted espionage implants against selected individuals rather than in mass or ransomware campaigns, and CISA does not flag any known ransomware use. Because the fix has been available since 2019, real residual risk sits almost entirely with unmanaged, stale or end-of-life devices. Organisations with exposed executives or KRITIS personnel should run the inventory check urgently, while a fully MDM-managed fleet with enforced updates should be able to close this out with minimal effort.
Runbook step 1
Immediate response (0-24 h)
- Inventory every WhatsApp install via MDM/UEM: Affected versions are WhatsApp for Android before v2.19.134, WhatsApp Business for Android before v2.19.44, WhatsApp and WhatsApp Business for iOS before v2.19.51, WhatsApp for Windows Phone before v2.18.348, and WhatsApp for Tizen before v2.18.15. Treat anything below these as exposed.
- Enforce a minimum app version: Set an app-compliance policy in Intune, Workspace ONE or Jamf. Block non-compliant devices from mail, VPN and corporate apps through Conditional Access until they update.
- Retire legacy platforms: Windows Phone and Tizen devices no longer receive vendor support. Flag them in the asset register, unbind corporate accounts and physically recover the hardware.
- Check high-exposure users first: Prioritise executives, negotiators, staff with government contact and anyone holding KRITIS control-system access. If any of them runs an outdated build, assume compromise until forensics says otherwise.
- On suspicion, isolate rather than wipe: Put the device in airplane mode but do not factory-reset it. Capture a forensic backup or sysdiagnose/bugreport first. Then rotate every credential that lived on the device, including SSO, VPN certificates and MFA seeds.
Runbook step 2
Mitigation layers
- IAM/access control: Tie device trust to app version (Intune "Min app version" or a compliance script). Revoke refresh tokens server-side for any device under suspicion.
- Network segmentation: Keep personal and BYOD phones on a dedicated guest/BYOD WLAN with no route into OT, management or server segments. A compromised handset must not become a pivot point into the internal network.
- Policy/configuration: For high-risk users, block WhatsApp on corporate devices via the MDM app blocklist and mandate a managed messenger instead. Evaluate iOS Lockdown Mode for this group.
- Mobile endpoint hardening: Deploy Mobile Threat Defense (e.g. Defender for Endpoint mobile, Lookout, Zimperium). Enable jailbreak/root detection and enforce automatic OS and app updates.
- Network controls: Blocking WhatsApp VoIP media (UDP RTP/RTCP via WhatsApp relays or STUN/TURN) on corporate Wi-Fi offers only partial protection, because attacks over cellular data bypass it entirely. Treat this as a supplementary control at most.
Runbook step 3
Detection rules
- MDM inventory as the primary source: Run this Defender KQL query:
DeviceTvmSoftwareInventory | where SoftwareName has "whatsapp" | project DeviceName, SoftwareName, SoftwareVersion. Compare the results against the fixed versions and schedule the query as a recurring compliance report. - User reports as an early warning: Unexplained missed WhatsApp calls from unknown (often international) numbers, followed by those entries vanishing from the call log, match the documented pattern of this zero-click attack. Have the service desk escalate such reports as security incidents.
- Forensic device triage: On suspicion, run the Mobile Verification Toolkit (MVT) against the iOS backup or Android bugreport. Look for anomalous processes, unknown configuration profiles and unusual WhatsApp crash logs (sysdiagnose/tombstones).
- Network telemetry (Zeek/Suricata, proxy): Flag mobile devices on corporate Wi-Fi that hold persistent connections to uncategorised domains or show unusual upload volume after an inbound VoIP call. A possible Sigma shape:
src_subnet=mobile AND bytes_out > baseline*5 AND dst_category=unknown. - MTD alerts: Forward privilege-escalation, sideloading and profile-install alerts from devices running outdated WhatsApp builds to the SIEM at top priority.
- MDM inventory as the primary source: Run this Defender KQL query:
Detection rules
No NEOSEC detection rule is available for this vulnerability yet.
Classification under NIS2 and CRA
Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.
NIS2
NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.
Read in glossary- Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
CRA
The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.
Read in glossary- Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
ISO/IEC 27001
ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.
Read in glossary- Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.
Description
A buffer overflow vulnerability in WhatsApp VOIP stack allowed remote code execution via specially crafted series of RTCP packets sent to a target phone number. The issue affects WhatsApp for Android prior to v2.19.134, WhatsApp Business for Android prior to v2.19.44, WhatsApp for iOS prior to v2.19.51, WhatsApp Business for iOS prior to v2.19.51, WhatsApp for Windows Phone prior to v2.18.348, and WhatsApp for Tizen prior to v2.18.15.
Source: NVD (NIST), cvelistv5, CISA KEV Catalog
Affected products
The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.
| Affected versions | Fixed in | ||
|---|---|---|---|
| WhatsApp Business for Android |
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| WhatsApp Business for iOS |
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| WhatsApp for Android |
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| WhatsApp for iOS |
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| WhatsApp for Tizen |
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| WhatsApp for Windows Phone |
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| whatsapp_business |
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Vendors and products
Weakness classes (CWE)
CWE-122Heap-based Buffer Overflow
Variant
A heap overflow condition is a buffer overflow, where the buffer that can be overwritten is allocated in the heap portion of memory, generally meaning that the buffer was allocated using a routine such as malloc().
Entry at MITRE CWE-122
Public exploit references
Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.
| CISA KEV Catalog | CISA Known Exploited Vulnerability (opens in a new tab)cisa.gov | actively exploited |
References & sources
- facebook.comsecurity/advisories/cve-2019-3568x_refsource_MISC, Third-party advisory
- securityfocus.com108329Vulnerability database, x_refsource_BID, Broken link, Third-party advisory, Vulnerability database
- cisa.govknown-exploited-vulnerabilities-catalog?field_cve=CVE-2019-3568government-resource, US government resource
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<a href="https://intel.neosec.eu/en/cve/CVE-2019-3568"><img src="https://intel.neosec.eu/badge/cve/CVE-2019-3568.svg?lang=en" alt="CVE-2019-3568 – NEOSEC Intel" height="20"></a>