Apple vulnerability CVE-2024-27834 is being actively exploited, the U.S. Cybersecurity and Infrastructure Security Agency said in its November 4, 2026 alert. Its addition to the Known Exploited Vulnerabilities (KEV) catalog raises the priority of applying available fixes across Safari and several Apple operating systems. Exploiting the flaw requires an attacker to already possess arbitrary memory read and write capabilities.
CISA classifies the issue as improper authentication affecting multiple Apple products. Security Affairs reports a CVSS score of 5.5 and describes its role in attacks attributed to Russia-linked cyberespionage group APT29. The severity score and the evidence of exploitation answer different questions: CISA’s listing confirms that attackers have used the vulnerability.
How the flaw advances an attack
The vulnerability undermines Pointer Authentication, a hardware security mechanism in Apple processors that uses cryptographic signatures to help detect tampered pointers. Those checks constrain an attacker’s ability to turn memory corruption into control over program execution.
Security Affairs quotes cybersecurity firm Sekoia explaining that, on modern Apple silicon, memory read and write access inside a browser renderer is insufficient by itself to complete an exploit. Replacing a function pointer with one that lacks a valid signature causes the process to crash. The reported attack chain uses CVE-2024-27834 to overcome that check and forge pointers that permit arbitrary code execution.
The bypass therefore helps attackers move beyond an existing memory-access capability, weakening defenses against memory-corruption attacks when combined with other vulnerabilities.
In the activity described by Sekoia and reported by Security Affairs, malicious JavaScript reached victims through compromised websites, fake websites and a supply-chain compromise involving Plerdy SEO Tracker. The researchers attributed the attacks to APT29 with moderate to high confidence.
The reported zero-click chain exploited vulnerabilities in Safari and Chrome, bypassed security protections and deployed information-stealing malware capable of gathering browser cookies and device data.
Fixes and remediation priorities
Security Affairs reports that Apple strengthened security checks to address CVE-2024-27834 in these releases:
- Safari 17.5.
- iOS 16.7.8 and iOS 17.5.
- iPadOS 16.7.8 and iPadOS 17.5.
- macOS Sonoma 14.5.
- tvOS 17.5.
- watchOS 10.5.
CISA’s alert places federal remediation requirements under Binding Operational Directive 26-04. That directive requires Federal Civilian Executive Branch agencies to prioritize rapid remediation of KEV vulnerabilities on publicly exposed assets where exploitation grants total control, while deferring lower-risk vulnerabilities. It also establishes expectations for checking whether systems were compromised before patching.
Security Affairs gives November 18, 2026 as the federal remediation deadline, citing BOD 22-01; CISA’s November 4 alert instead describes the BOD 26-04 framework. These binding requirements apply to covered federal civilian agencies. CISA encourages other organizations to use risk-based vulnerability management and prioritize KEV entries as well.
Administrators managing affected Apple products should prioritize the applicable security updates and verify that their deployments have received the fix for CVE-2024-27834, using the product and release-train distinctions above.
