CVE-2026-23866

Description

Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for iOS v2.25.8.0 to v2.26.15.72 and WhatsApp for Android v2.25.8.0 to v2.26.7.10 could have allowed a user to trigger processing of media content from an arbitrary URL on another user’s device, including triggering OS-controlled custom URL scheme handlers. We have not seen evidence of exploitation in the wild.

CVSS v3.1 Score

4.3

MEDIUM

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

EPSS — Exploit Prediction

0.0001

Probability of exploitation

0.01%

Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-940 CWE-940

Affected Products

Vendor	Product	Versions
whatsapp	whatsapp	2.25.8.0 — 2.26.7.10
whatsapp	whatsapp	2.25.8.0 — 2.26.15.72

References

Advisories & Patches

https://www.whatsapp.com/security/advisories/2026

Other References

https://www.facebook.com/security/advisories/cve-2026-23866

Frequently Asked Questions

What is CVE-2026-23866? +

Incomplete validation of AI rich response messages for Instagram Reels in WhatsApp for iOS v2.25.8.0 to v2.26.15.72 and WhatsApp for Android v2.25.8.0 to v2.26.7.10 could have allowed a user to trigger processing of media content from an arbitrary URL on another user’s device, including triggering OS-controlled custom URL scheme handlers. We have not seen evidence of exploitation in the wild. It has a CVSS v3.1 base score of 4.3 (MEDIUM).

How severe is CVE-2026-23866? +

CVE-2026-23866 has a CVSS v3.1 score of 4.3 out of 10, rated MEDIUM. This is a medium-severity vulnerability that should be remediated as part of regular maintenance. The EPSS score is 0.0001, placing it in the 0th percentile for exploitation probability.

What products are affected by CVE-2026-23866? +

CVE-2026-23866 affects products from whatsapp, specifically: whatsapp. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2026-23866? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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