CriticalCVE-2023-41064

    Apple iOS, iPadOS, and macOS ImageIO Buffer Overflow Vulnerability (CVE-2023-41064)

    Published In CISA KEV since Sources: CVE.org, SingCERT, pwn.watch

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    What is affected, what to do

    A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 16.6.1 and iPadOS 16.6.1, macOS Monterey 12.6.9, macOS Ventura 13.5.2, iOS 15.7.9 and iPadOS 15.7.9, macOS Big Sur 11.7.10.

    The vulnerability is being actively exploited; treat it as a priority. Update Apple macOS to version 12.6, Apple macOS to version 11.7, Apple iOS and iPadOS to version 16.6. Immediate actions, mitigation and detection rules are in the runbook below.

    Affected
    • Apple macOS lt *..12.6
    • Apple macOS lt *..11.7
    • Apple iOS and iPadOS lt *..16.6
    • Apple iOS and iPadOS lt *..15.7
    • Apple macOS lt *..13.5
    Fixed in
    • Apple macOS 12.6
    • Apple macOS 11.7
    • Apple iOS and iPadOS 16.6
    • Apple iOS and iPadOS 15.7
    • Apple macOS 13.5

    Not sure whether and how you are affected? Ask a question about this vulnerability

    Metrics

    7.8

    Priority

    XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

    Source: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: CVE.org, SingCERT, pwn.watch

    53.4 %

    EPSS score

    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.

    Source: FIRST EPSS, percentile 99.0

    Show all metrics
    Severity
    Critical
    Priority (0–325)

    The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first?

    Read in glossary
    220.73 Methodology
    Exploit maturity

    An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack.

    Read in glossary
    actively exploitedSource: Apple (CVE.org), CSA/SingCERT How we classify
    XIEM Effective CVSS

    XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command.

    Read in glossary
    7.8 Methodology
    CVSS v3

    CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions.

    Read in glossary
    7.8
    EPSS score

    The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“.

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    53.4 %
    High — model estimates ≥ 50% chance of real-world exploitation within 30 days.
    EPSS percentile

    The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking.

    Read in glossary
    99.0
    Critical — this CVE ranks in the top fifth of all CVEs scored today (rank ≥ 80%).
    KEV status

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    Actively exploited
    Published
    In CISA KEV since

    The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching.

    Read in glossary
    CISA assessment (SSVC)
    Exploitation: active · automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 15 November 2023
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-120

    Response and mitigation

    Why act now?

    Prioritisation rationale

    This CVE is on KEV because it was used as part of a zero-click chain with CVE-2023-41061: a crafted image delivered in a message is enough to execute code with no meaningful user interaction. The nominal "local, user interaction required" rating therefore understates the real-world risk considerably. CISA lists no known ransomware use; the typical target profile is selected individuals such as executives, government officials, journalists and staff with access to sensitive or safety-critical information. Exploitation likelihood is very high, so NIS2/KRITIS organisations should treat the rollout as critical, especially for mobile devices used by leadership or holding privileged access. The fix has been available for a long time, so any device still unpatched is a compliance and governance finding in its own right.

    1. Runbook step 1

      Immediate response (0-24 h)

      • Patch now: Update iOS/iPadOS to 16.6.1 or 15.7.9 (older hardware), and macOS to Ventura 13.5.2, Monterey 12.6.9 or Big Sur 11.7.10. Push enforced updates via MDM (Intune, Jamf, Workspace ONE) with a deadline of 24 hours or less, and force the reboot.
      • Scope the fleet: Export every device below those versions from MDM. Patch executives, board members, OT/control-room leads, press/comms staff and admins first, because this chain is used against hand-picked individuals.
      • Gate access: Flag unpatched iOS/iPadOS/macOS devices as non-compliant and block access to M365, VPN, mail and collaboration platforms via Conditional Access until they are updated.
      • Lockdown Mode for high-risk users: Enable Apple Lockdown Mode on devices of exposed personnel. It restricts message attachment and image-preview processing and substantially shrinks the attack surface of this chain, which is paired with CVE-2023-41061 in Wallet/PassKit.
      • Retire unsupported hardware: Devices that cannot reach iOS 16.6.1 or 15.7.9 should be cut off from corporate networks and data immediately, and a replacement should be scheduled.

    2. Runbook step 2

      Mitigation layers

      • Configuration / endpoint hardening: On high-risk devices, disable iMessage and FaceTime via MDM profile where they are not business-critical, and restrict automatic image previews in Mail and messengers. Until the patch lands, Lockdown Mode is the single most effective compensating control.
      • Mail and web gateway: Quarantine or sandbox-detonate image attachments whose extension does not match their magic bytes (e.g. WebP disguised as .png/.jpg), as well as externally sourced .pkpass files. Re-render image attachments through content disarm and reconstruction (CDR).
      • Network segmentation: Place mobile devices in a dedicated Wi-Fi/VPN segment with no direct path to management networks, OT/ICS zones or jump hosts. A compromised phone must not become a pivot into critical-infrastructure zones.
      • IAM / least privilege: Do not allow push-approval MFA for privileged accounts from unpatched devices; prefer FIDO2 hardware keys. Revoke session tokens for users of affected devices once they have been updated.
      • Mobile Threat Defense: Where MTD is deployed (Defender for Endpoint mobile, Lookout, Zimperium), raise "vulnerable OS version" to high risk and tie it into Conditional Access.

    3. Runbook step 3

      Detection rules

      • MDM/inventory telemetry: Run a daily compliance report covering OSVersion < 16.6.1 (iOS 16 branch), < 15.7.9 (iOS 15 branch), and < 13.5.2 / < 12.6.9 / < 11.7.10 (macOS). Open an incident ticket for any device still vulnerable after the deadline.
      • macOS EDR, process ancestry: Alert on image-handling processes that spawn shells or network tools. KQL (Defender for Endpoint): DeviceProcessEvents | where InitiatingProcessFileName in~ ("Preview","QuickLookUIService","IMTranscoderAgent","MessagesBlastDoorService","Mail") and FileName in~ ("sh","bash","zsh","osascript","curl","python3").
      • Crash reports as an early signal: Watch for clusters of crashes in imagent, IMTranscoderAgent or MessagesBlastDoorService, or crashes with ImageIO frames in the stack. On macOS, check /Library/Logs/DiagnosticReports and ~/Library/Logs/DiagnosticReports; on iOS, pull analytics via sysdiagnose. These can indicate failed exploitation attempts.
      • iOS forensic triage: If compromise is suspected, collect a backup or sysdiagnose and analyse it with the Mobile Verification Toolkit (MVT) against current public IOC sets. Focus on PassKit-type iMessage attachments and unusual images from unknown senders.
      • Gateway logs: Use a Sigma-style rule on mail gateway logs: attachment.extension in (png, jpg, gif) AND attachment.detected_type == "webp" or attachment.extension == "pkpass" AND sender.external == true. Escalate hits on high-risk recipients.

    Detection rules

    No NEOSEC detection rule is available for this vulnerability yet.

    Classification under NIS2 and CRA

    Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

    NIS2

    NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management.

    Read in glossary
    Actively exploited: treat the vulnerability as a priority in vulnerability handling under Art. 21(2)(e) NIS2. If it is exploited in your environment, check the reporting obligation under Art. 23 (early warning within 24 hours).
    CRA

    The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates.

    Read in glossary
    Since 11.09.2026, manufacturers of affected products with digital elements must report actively exploited vulnerabilities under Art. 14 CRA, with an early warning within 24 hours via ENISA's single reporting platform.
    ISO/IEC 27001

    ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security.

    Read in glossary
    Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

    Description

    A buffer overflow issue was addressed with improved memory handling. This issue is fixed in iOS 16.6.1 and iPadOS 16.6.1, macOS Monterey 12.6.9, macOS Ventura 13.5.2, iOS 15.7.9 and iPadOS 15.7.9, macOS Big Sur 11.7.10. Processing a maliciously crafted image may lead to arbitrary code execution. Apple is aware of a report that this issue may have been actively exploited.

    Source: cvelistv5, CSA/SingCERT, pwn.watch, NVD (NIST), CISA KEV Catalog, CVE.org (MITRE)

    Affected products

    The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

    Affected products
    Affected versionsFixed in
    AppleiOS and iPadOS
    • < 16.6
    • < 15.7
    • 16.6
    • 15.7
    ApplemacOS
    • < 12.6
    • < 11.7
    • < 13.5
    • 12.6
    • 11.7
    • 13.5

    Vendors and products

    Affected operating systems

    Affected operating systems
    macOSapplemacos—
    Mobileappleiphone_os—
    Otherappleipados—

    Weakness classes (CWE)

    • CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

      Base

      The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer.

      Entry at MITRE CWE-120

    Public exploit references

    Publicly reported proof-of-concepts, exploit modules and detection templates for this vulnerability. NEOSEC links to the original sources only and does not provide any exploit code.

    Public exploit references
    CISA KEV CatalogCISA Known Exploited Vulnerability (opens in a new tab)cisa.govactively exploited
    Apple (CVE.org)CVE.org (MITRE) (opens in a new tab)actively exploited
    CSA/SingCERTActive Exploitation of Zero-Day Vulnerabilities in Apple Products (opens in a new tab)CSA/SingCERTactively exploited

    References & sources

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