CVE-2026-4984

High

Published: 27 March 2026

Published

27 March 2026

Modified

10 May 2026

KEV Added

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Patch

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CVSS Score 8.2 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N

EPSS Score 0.0004 13.5th percentile

Risk Priority 16 60% EPSS · 20% KEV · 20% CVSS

Summary

CVE-2026-4984 is a high-severity Insufficient Verification of Data Authenticity (CWE-345) vulnerability. Its CVSS base score is 8.2 (High).

Operationally, exploitation aligns with the MITRE ATT&CK technique Exploit Public-Facing Application (T1190); ranked at the 13.5th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog.

The strongest mitigations our analysis identified are NIST 800-53 IA-9 (Service Identification and Authentication) and SI-10 (Information Input Validation).

Threat & Defense at a Glance

What attackers do: exploitation maps to Exploit Public-Facing Application (T1190) and 1 other technique. What defenders deploy: see the NIST 800-53 controls recommended below.

Threat & Defense Details

Mitigating Controls (NIST 800-53 r5)AI

IA-9 Service Identification and Authentication good match

prevent

Requires identification and authentication of external services like Twilio webhooks using 'X-Twilio-Signature' before processing payloads, directly preventing forged requests.

SI-10 Information Input Validation good match

prevent

Mandates validation of information inputs including webhook signatures and 'MediaUrlN' parameters to block malicious payloads and untrusted URLs.

SC-7 Boundary Protection partial match

prevent

Monitors and controls communications at system boundaries to restrict outbound HTTP requests carrying Twilio credentials to attacker-controlled servers.

MITRE ATT&CK Enterprise TechniquesAI

T1190 Exploit Public-Facing Application Initial Access

Adversaries may attempt to exploit a weakness in an Internet-facing host or system to initially access a network.

attack.mitre.org →

T1528 Steal Application Access Token Credential Access

Adversaries can steal application access tokens as a means of acquiring credentials to access remote systems and resources.

attack.mitre.org →

Why these techniques?

Vulnerability in unauthenticated public webhook handler enables direct exploitation of public-facing application (T1190) to force leakage of Twilio API credentials, directly facilitating theft of application access tokens (T1528) for account compromise.

Confidence: HIGH · MITRE ATT&CK Enterprise v18.1

NVD Description

The Twilio integration webhook handler accepts any POST request without validating Twilio's 'X-Twilio-Signature'. When processing media messages, it fetches user-controlled URLs ('MediaUrlN' parameters) using HTTP requests that include the integration's Twilio credentials in the 'Authorization' header. An attacker can forge…

a webhook payload pointing to their own server and receive the victim's 'accountSID' and 'authToken' in plaintext (base64-encoded Basic Auth), leading to full compromise of the Twilio account.

Deeper analysisAI

CVE-2026-4984 affects the Twilio integration webhook handler, which accepts any POST request without validating Twilio's 'X-Twilio-Signature'. When processing media messages, the handler fetches user-controlled URLs specified in 'MediaUrlN' parameters via HTTP requests that include the integration's Twilio credentials in the 'Authorization' header. Published on 2026-03-27, this flaw has a CVSS v3.1 base score of 8.2 (AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:L/A:N).

An unauthenticated attacker (PR:N) can exploit this remotely over the network (AV:N) with low complexity (AC:L) by forging a webhook payload that points 'MediaUrlN' to a server they control. Upon processing, the handler sends an HTTP request to the attacker's server, exposing the victim's Twilio 'accountSID' and 'authToken' in plaintext within a base64-encoded Basic Auth 'Authorization' header, enabling full compromise of the Twilio account.

The Tenable advisory at https://www.tenable.com/security/research/tra-2026-22 provides further details on mitigation.