CVE-2026-28920Network attack vector

Sensitive-data disclosure via uninitialized inflate memory

Published May 11, 2026 · Updated May 11, 2026

Information disclosure in Apple zlib across iOS, iPadOS, macOS, tvOS, visionOS, and watchOS allows remote attackers to read sensitive data. During inflate decompression, Apple zlib returns bytes from uninitialized memory when processing crafted compressed input embedded in a malicious website. Exploitation requires a user to visit attacker-controlled web content; no integrity or availability impact is published.

CVSS severity6.5
Medium
EPSS probability0.32%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Information disclosure in Apple zlib across iOS, iPadOS, macOS, tvOS, visionOS, and watchOS allows remote attackers to read sensitive data. During inflate decompression, Apple zlib returns bytes from uninitialized memory when processing crafted compressed input embedded in a malicious website. Exploitation requires a user to visit attacker-controlled web content; no integrity or availability impact is published.

The record

CVE
CVE-2026-28920
Published
May 11, 2026
Updated
May 11, 2026
Vendor
Apple
Product
iOS and iPadOS
Classifications
CWE-200, 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 <14.8.7; version=0 <15.7.7; version=0 <26.5
Apple · watchOSversion=0 <26.5

Published CVSS scores

6.5CISA-ADPCVSS:3.1/AV:N/AC:L/PR:N/UI:R/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-200Exposure of Sensitive Information to an Unauthorized Actor
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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