CVE-2026-43660Network attack vector

CSP bypass via overwritten blob policy headers

Published May 11, 2026 · Updated May 11, 2026

WebKit in affected Apple operating systems allows remote attackers to bypass Content Security Policy through crafted web content. ContentSecurityPolicyResponseHeaders::addPolicyHeadersTo() uses setHTTPHeaderField() when copying multiple policies to a blob response, so each write overwrites the preceding header and leaves only the final policy. A page must supply two or more CSP headers and create a blob URL; affected releases are iOS and iPadOS before 18.7.9 or 26.5 and macOS, tvOS, visionOS, and watchOS before 26.5, with the bounded consequence that the blob document loses all but the final policy.

CVSS severity7.5
High
EPSS probability0.27%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

WebKit in affected Apple operating systems allows remote attackers to bypass Content Security Policy through crafted web content. ContentSecurityPolicyResponseHeaders::addPolicyHeadersTo() uses setHTTPHeaderField() when copying multiple policies to a blob response, so each write overwrites the preceding header and leaves only the final policy. A page must supply two or more CSP headers and create a blob URL; affected releases are iOS and iPadOS before 18.7.9 or 26.5 and macOS, tvOS, visionOS, and watchOS before 26.5, with the bounded consequence that the blob document loses all but the final policy.

The record

CVE
CVE-2026-43660
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-693, T1189
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 11, 2026CVE publishedPublication date reported by the CVE source.
  2. May 11, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <18.7.9
  2. Affected versionversion=0 <26.5

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOS and iPadOSversion=0 <18.7.9; version=0 <26.5
Apple · visionOSversion=0 <26.5
Apple · tvOSversion=0 <26.5
Apple · macOSversion=0 <26.5
Apple · watchOSversion=0 <26.5

Published CVSS scores

7.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-693Protection Mechanism Failure
T1189Drive-by Compromise

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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