CVE-2019-8741Network attack vector

Service hang via oversized CoreCrypto hash input

Published Feb 28, 2020 · Updated Aug 4, 2024

Denial of service in CoreCrypto across affected Apple systems and Windows clients allows remote attackers to hang cryptographic operations. Eleven hash implementations, plus operations including HMAC and Ed25519, enter an infinite loop on inputs around 4 GiB instead of returning output. Reachability requires a consuming application to pass attacker-controlled data of that size into CoreCrypto; the affected operation then remains stuck.

CVSS severity7.5
High
EPSS probability2.46%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
Coverage for this vulnerability

See if you're affected

Explore vulnerability checks for your environment with Hinoki.

Book a demo

Summary

What happened

Denial of service in CoreCrypto across affected Apple systems and Windows clients allows remote attackers to hang cryptographic operations. Eleven hash implementations, plus operations including HMAC and Ed25519, enter an infinite loop on inputs around 4 GiB instead of returning output. Reachability requires a consuming application to pass attacker-controlled data of that size into CoreCrypto; the affected operation then remains stuck.

The record

CVE
CVE-2019-8741
Published
Feb 28, 2020
Updated
Aug 4, 2024
Vendor
Apple
Product
iOS
Classifications
CWE-835, T1499.004
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 28, 2020CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=unspecified <iOS 13

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Apple · iOSversion=unspecified <iOS 13
Apple · iTunes for Windowsversion=unspecified <iTunes for Windows 12.10.1
Apple · iCloud for Windows (Legacy)version=unspecified <iCloud for Windows 7.14
Apple · iCloud for Windowsversion=unspecified <iCloud for Windows 10.7
Apple · tvOSversion=unspecified <tvOS 13
Apple · macOSversion=unspecified <macOS Catalina 10.15
Apple · watchOSversion=unspecified <watchOS 6

Published CVSS scores

7.5NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.8NIST NVDAV:N/AC:L/Au:N/C:N/I:N/A:C

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-835Loop with Unreachable Exit Condition ('Infinite Loop')
T1499.004Application or System Exploitation

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

See the directory against your own environment.

Your stack

Check the software in your environment

Book a demo to see how Hinoki identifies affected software and validates exploitability in your environment.

Book a demo