External risk intelligence

Apple WebKit Cross-Site Scripting Vulnerability

CVE advisoryKnown Exploit

CVE-2021-1879

A vulnerability in Apple's operating systems could permit cross-site scripting when processing malicious web content. This may affect organizations using these systems, leading to unauthorized actions or data exposure. Active exploitation has been reported, posing a business risk.

3Halo Surface Signal

Cross-site Scripting

Apple Ipados

before 14.4.2before 12.5.213.0 to before 14.4.2before 7.3.3

External exposure likelihood

Halo Surface Signal score for CVE-2021-1879

This vulnerability resides in the WebKit engine used by Apple mobile devices. While it is triggered by processing web content, requiring a user to visit a malicious site or interact with content, it is not a public-facing service or listener by design. It represents a client-side execution risk rather than an internet-facing service or appliance portal.

Horizon Alert

Summary of the vulnerability and why it matters

This vulnerability affects Apple's operating systems, specifically how they handle web content. A flaw in object lifetime management within the WebKit framework could allow malicious web content to execute scripts. This could potentially expose sensitive information or allow unauthorized actions within the affected systems.

  • Vulnerable: Apple operating systems (iOS, iPadOS, watchOS)
  • Flaw: Improper object lifetime management
  • Impact: Cross-site scripting execution

Attack Path

How an attacker could exploit the issue

The attack begins when an organization's systems encounter specially crafted web content. An attacker can then leverage this exposure to gain access. The interaction with malicious content triggers the vulnerability, leading to unauthorized control or impact. Apple has stated that this issue may have been actively exploited.

  • Exposure through web content.
  • Attacker accesses via malicious site.
  • Triggering action results in impact.

Live Threat

Current exploitation, exposure, and threat context

A vulnerability in Apple's WebKit could allow attackers to execute cross-site scripting through maliciously crafted web content. This means organizations could face risks if employees interact with malicious websites or content. The reported active exploitation suggests a potential for broad impact across affected systems.

  • Attackers require low skill.
  • Users must visit malicious sites.
  • Business risk is moderate.

Priority actions

Operational Fix

Recommended remediation, mitigation, and detection steps

This vulnerability, present in Apple's WebKit, could allow attackers to execute cross-site scripting through maliciously crafted web content. Organizations should prioritize actions to identify and address affected systems. The known exploited status of this issue warrants immediate attention to mitigate business risk.

  • Find affected Apple devices.
  • Reduce exposure or isolate risk.
  • Apply vendor fixes and verify.
  • Monitor for related issues.

Frequently asked questions

What is CVE-2021-1879, a vulnerability in Apple's WebKit?

CVE-2021-1879 is a security flaw within Apple's WebKit, the core technology for rendering web pages on devices like iPhones, iPads, and Apple Watches. The vulnerability arises from how WebKit manages the memory associated with objects, which, if exploited through specially crafted web content, can lead to a universal cross-site scripting (XSS) attack. Apple has acknowledged reports of this vulnerability being actively exploited.

How is CVE-2021-1879 classified and what is its root cause?

This vulnerability is categorized as a weakness related to improper handling of object lifetimes, specifically resulting in a universal cross-site scripting (XSS) vulnerability. The root cause is the way WebKit manages the lifespan of objects, which can be manipulated by malicious web content to execute scripts.

What is the trigger path and scope of CVE-2021-1879?

The vulnerability is triggered when an affected Apple device processes maliciously crafted web content. This could occur when a user visits a compromised website or interacts with malicious content within an application that utilizes WebKit. The scope of the impact can be universal cross-site scripting, meaning an attacker could potentially inject malicious scripts that execute within the context of the user's browser session.

What is the relevance of CVE-2021-1879, considering its active exploitation?

The relevance of CVE-2021-1879 is heightened by reports that it has been actively exploited. This indicates a real-world threat where attackers are leveraging this flaw. Given its presence in widely used Apple operating systems, organizations with affected devices face a potential risk if their users encounter malicious web content, as highlighted by Halo's assessment of possible threat.

What practical steps should organizations take to respond to CVE-2021-1879?

Organizations should promptly identify all Apple devices running vulnerable versions of iOS, iPadOS, and watchOS. Applying the security updates provided by Apple for these operating systems is crucial to remediate the vulnerability. Verifying that updates have been successfully installed and monitoring for any related security incidents are also recommended steps to mitigate business risk.

References