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VulnerabilityPublished Updated

CVE-2026-20643: Apple Safari · Improper Input Validation

Affects Apple SafariSource CVE Database V5

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Not known to be exploited · CVSS 5.4 Medium : upgrade to 26.4 when convenient.

Data as of 30 Oct 2026, 12:04 UTC

CVSS 3.1 base score
5.4Medium
How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none
CVSS scores by source
CISA-ADPCVSS 3.15.4
EPSS
0.3% chance of exploitation in 30 days – higher than 29% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 26.4, 18.7.7
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 17 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: evidence found.

    Public exploit code: GitHub proofs of concept

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), GitHub proofs of concept, the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade Safari and macOS and visionOS to 26.4; iOS and iPadOS to 26.4 or 18.7.7.

Affected software

ProductAffectedFixed in
AppleSafariAffected
  • <26.4
Fixed in
  • 26.4
AppleiOS and iPadOSAffected
  • <18.7.7
  • <26.4
Fixed in
  • 26.4
  • 18.7.7
ApplemacOSAffected
  • <26.4
Fixed in
  • 26.4
ApplevisionOSAffected
  • <26.4
Fixed in
  • 26.4

AI-suggested

Organizations and users should promptly update Safari and their operating systems to the patched versions: Safari 26.4, iOS 18.7.7 and 26.4, iPadOS 18.7.7 and 26.4, macOS Tahoe 26.4, and visionOS 26.4. Enforce strict update policies for Apple devices to ensure timely deployment of security patches. Employ web content filtering and monitoring to detect and block access to known malicious sites that could exploit this vulnerability. Educate users about the risks of interacting with untrusted websites and encourage cautious browsing behavior. Implement Content Security Policy (CSP) headers on organizational web applications to restrict the execution of unauthorized scripts and reduce the impact of cross-origin attacks. Use network-level protections such as DNS filtering and secure web gateways to reduce exposure to malicious web content. Monitor browser telemetry and logs for unusual cross-origin requests or navigation behaviors that could indicate exploitation attempts. For high-security environments, consider restricting or controlling the use of Safari until patches are applied.

Description

A cross-origin issue in the Navigation API was addressed with improved input validation. This issue is fixed in Background Security Improvements for iOS, iPadOS, and macOS, Safari 26.4, iOS 18.7.7 and iPadOS 18.7.7, iOS 26.4 and iPadOS 26.4, macOS Tahoe 26.4, visionOS 26.4. Processing maliciously crafted web content may bypass Same Origin Policy.

References

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