WhatsApp has addressed a security vulnerability in its messaging apps for Apple iOS and macOS that it said may have been exploited in the wild in conjunction with a recently disclosed Apple flaw in targeted zero-day attacks.
The vulnerability, CVE-2025-55177 (CVSS score: 5.4), relates to a case of insufficient authorization of linked device synchronization messages. Internal researchers on the WhatsApp Security Team have been credited with discovering and rerating the bug.
The Meta-owned company said the issue “could have allowed an unrelated user to trigger processing of content from an arbitrary URL on a target’s device.”
The flaw affects the following versions –
- WhatsApp for iOS prior to version 2.25.21.73 (Patched on July 28, 2025)
- WhatsApp Business for iOS version 2.25.21.78 (Patched on August 4, 2025), and
- WhatsApp for Mac version 2.25.21.78 (Patched on August 4, 2025)
It also assessed that the shortcoming may have been chained with CVE-2025-43300, a vulnerability affecting iOS, iPadOS, and macOS, as part of a sophisticated attack against specific targeted users.
CVE-2025-43300 was disclosed by Apple last week as having been weaponized in an “extremely sophisticated attack against specific targeted individuals.”
The vulnerability in question is an out-of-bounds write vulnerability in the ImageIO framework that could result in memory corruption when processing a malicious image.
Donncha Ó Cearbhaill, head of the Security Lab at Amnesty International, said WhatsApp has notified an unspecified number of individuals that they believe were targeted by an advanced spyware campaign in the past 90 days using CVE-2025-55177.
In the alert sent to the targeted individuals, WhatsApp has also recommended performing a full device factory reset and keeping their operating system and the WhatsApp app up-to-date for optimal protection. It’s currently not known who, or which spyware vendor, is behind the attacks.
Ó Cearbhaill described the pair of vulnerabilities as a “zero-click” attack, meaning it does not require any user interaction, such as clicking a link, to compromise their device.
“Early indications are that the WhatsApp attack is impacting both iPhone and Android users, civil society individuals among them,” Ó Cearbhaill said. “Government spyware continues to pose a threat to journalists and human rights defenders.”
Update
In a statement shared with The Hacker News, WhatsApp said it sent in-app threat notifications to less than 200 users who may have been targeted as part of the campaign.
(The story was updated after publication to clarify that patches were released for the flaw in late July/August 2025. It was updated again on September 2, 2025, to reflect the latest CVSS score published in the NIST NVD database.)
