VulnerabilityPublished 25 Mar 2026Updated 26 Oct 2026

CVE-2026-20665: Apple Safari · Processing maliciously crafted web content may prevent Content Security Policy from being enforced in

Affects Apple SafariSource CVE Database V5

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Not known to be exploited · CVSS 6.5 Medium : upgrade to 26.4 when convenient.

Data as of 29 Oct 2026, 19:15 UTC

CVSS 3.1 base score

6.5Medium

How severe the flaw is on the 0–10 CVSS scale.

Thin evidence

One scorer or none

CVSS scores by source
CISA-ADP	CVSS 3.1	6.5

EPSS: 0.6% chance of exploitation in 30 days – higher than 50% 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:N/S:U/C:L/I:N/A:L

Attack Vector: Network
Attack Complexity: Low
Privileges Required: None
User Interaction: None
Scope: Unchanged
Confidentiality: Low
Integrity: None
Availability: Low

Bold values are the worst case: easiest to exploit or largest impact.

Attack Vector: Network: The vulnerable component is bound to the network stack and the set of possible attackers extends beyond the other options listed, up to and including the entire Internet. Such a vulnerability is often termed 'remotely exploitable' and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers).
Attack Complexity: Low: Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success against the vulnerable component.
Privileges Required: None: The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files to carry out an attack.
User Interaction: None: The vulnerable system can be exploited without any interaction from any user.
Scope: Unchanged: An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority.
Confidentiality: Low: There is some loss of confidentiality. Access to some restricted information is obtained, but the attacker does not have control over what information is obtained, or the amount or kind of loss is limited. The information disclosure does not cause a direct, serious loss to the impacted component.
Integrity: None: There is no loss of integrity within the impacted component.
Availability: Low: Performance is reduced or there are interruptions in resource availability. Even if repeated exploitation of the vulnerability is possible, the attacker does not have the ability to completely deny service to legitimate users. The resources in the impacted component are either partially available all of the time, or fully available only some of the time, but overall there is no direct, serious consequence to the impacted component.

Definitions: FIRST CVSS v3.1 specification.

Exploitation evidence

Disclosed: evidence found.
CVE published 25 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by 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), the Metasploit, Exploit-DB and nuclei-templates index as of 29 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

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

Affected software

Product	Affected	Fixed in
AppleSafari	Affected <26.4	Fixed in 26.4
AppleiOS and iPadOS	Affected <26.4	Fixed in 26.4
AppleiOS and iPadOS	Affected <18.7.7	Fixed in 18.7.7
ApplemacOS	Affected <26.4	Fixed in 26.4
AppletvOS	Affected <26.4	Fixed in 26.4
ApplevisionOS	Affected <26.4	Fixed in 26.4

AI-suggested

Immediately update all affected Apple platforms to Safari 26.4 or later and corresponding OS versions (iOS 18.7.7, iPadOS 18.7.7, macOS Tahoe 26.4, tvOS 26.4, visionOS 26.4, watchOS 26.4) to ensure the vulnerability is patched.
Enforce strict CSP headers with nonce or hash-based directives to reduce reliance on default policies and minimize the impact of potential CSP bypasses.
Implement web application security best practices such as input validation, output encoding, and use of Subresource Integrity (SRI) to complement CSP protections.
Monitor web traffic and logs for unusual script execution or resource loading patterns that may indicate exploitation attempts.
Educate users about the risks of visiting untrusted websites and encourage use of updated browsers.
For enterprise environments, consider deploying network-level web filtering and sandboxing solutions to reduce exposure to malicious web content.
Regularly review and audit CSP implementations to ensure policies are correctly configured and enforced.

Description

This issue was addressed through improved state management. This issue is fixed in Safari 26.4, iOS 18.7.7 and iPadOS 18.7.7, iOS 26.4 and iPadOS 26.4, macOS Tahoe 26.4, tvOS 26.4, visionOS 26.4, watchOS 26.4. Processing maliciously crafted web content may prevent Content Security Policy from being enforced.

Impact

The primary impact of CVE-2026-20665 is the potential bypass of Content Security Policy enforcement in Safari browsers, which undermines a key security control designed to prevent malicious script execution and resource loading. This can lead to partial loss of confidentiality if attackers manage to execute unauthorized scripts that steal sensitive information such as cookies, tokens, or user data. The integrity impact is minimal as the vulnerability does not directly allow data modification, but it can be a stepping stone for further attacks. Availability impact is low to medium since malicious content could disrupt normal browser behavior or cause denial of service conditions. Because the vulnerability requires no privileges or user interaction and can be exploited remotely via crafted web content, it poses a significant risk to users visiting malicious or compromised websites. Organizations relying on Apple devices for web access, especially those enforcing strict CSP policies for internal or web applications, may face increased risk of web-based attacks, data leakage, and compliance violations if patches are not applied promptly.

CWE-693Protection Mechanism Failure (opens in a new tab)
Pillar weaknessOWASP Top 10 A06:2025: Insecure Design (opens in a new tab)
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product.
MITRE discourages mapping vulnerabilities to this broad entry; the root cause is usually a more specific weakness.
OWASP Cheat Sheets
Secure Design Principles (opens in a new tab)
Attack patterns
Accessing Functionality Not Properly Constrained by ACLs (opens in a new tab)
Cross Site Tracing (opens in a new tab)
Directory Indexing (opens in a new tab)
Using Malicious Files (opens in a new tab)
Encryption Brute Forcing (opens in a new tab)
From MITRE CWE, MITRE CAPEC and OWASP (Top 10, OpenCRE).

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 3 Apr 2026, 02:57 UTC

WeaknessesCWE-693

Technical details

References

Community reviews

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