cbcvebase.
CVE-2019-8689
published 2019-12-18

CVE-2019-8689: Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in iOS 12.4, macOS Mojave 10.14.6, tvOS 12.4, watchOS 5.3…

PriorityP268high8.8CVSS 3.1
AVNACLPRNUIRSUCHIHAH
EXPLOIT
EPSS
12.85%
95.9th percentile
Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in iOS 12.4, macOS Mojave 10.14.6, tvOS 12.4, watchOS 5.3, Safari 12.1.2, iTunes for Windows 12.9.6, iCloud for Windows 7.13, iCloud for Windows 10.6. Processing maliciously crafted web content may lead to arbitrary code execution.

Affected

28 ranges· showing 25
VendorProductVersion rangeFixed in
appleicloud< 7.137.13
appleicloud>= 10.0 < 10.610.6
appleicloud_for_windows
appleicloud_for_windows
appleicloud_for_windows>= unspecified < iCloud for Windows 7.13iCloud for Windows 7.13
appleicloud_for_windows>= unspecified < iCloud for Windows 10.6iCloud for Windows 10.6
appleios
appleios>= unspecified < iOS 12.4iOS 12.4
appleiphone_os< 12.412.4
appleitunes< 12.9.612.9.6
appleitunes_12.9.6_for_windows
appleitunes_for_windows>= unspecified < iTunes for Windows 12.9.6iTunes for Windows 12.9.6
applemac_os_x< 10.14.610.14.6
applemacos>= unspecified < macOS Mojave 10.14.6macOS Mojave 10.14.6
applemacos_mojave_10.14.6_security_update_2019-004_high_sierra_security_update_2019-0
applesafari< 12.1.212.1.2
applesafari
applesafari>= unspecified < Safari 12.1.2Safari 12.1.2
appletvos< 12.412.4
appletvos
appletvos>= unspecified < tvOS 12.4tvOS 12.4
applewatchos< 5.35.3
applewatchos
applewatchos>= unspecified < watchOS 5.3watchOS 5.3
debianwebkit2gtk< webkit2gtk 2.24.3-1 (bookworm)webkit2gtk 2.24.3-1 (bookworm)

Detection & IOCsextracted from sources · hover to see the quote

urlhttps://github.com/WebKit/webkit/blob/94e868c940d46c5745869192d07255331d00102b/Source/JavaScriptCore/dfg/DFGArgumentsEliminationPhase.cpp#L743
pathSource/JavaScriptCore/dfg/DFGArgumentsEliminationPhase.cpp
  • The vulnerability is triggered by JIT-compiled JavaScript that accesses rest parameters with a negative or overflow index (e.g., -1 or 0xffffffff) via GetByVal on a PhantomCreateRest node in WebKit's DFG JIT ArgumentsEliminationPhase. Monitor for JavaScript executing large loop counts (~1,000,000 iterations) to trigger JIT compilation followed by rest-parameter index underflow access.
  • The root cause is in WebKit JSC DFGArgumentsEliminationPhase::transform — the GetByVal case does not check whether 'index' is lower than 'numberOfArgumentsToSkip', allowing integer underflow/overflow leading to uninitialized variable access. Detection should focus on WebKit/JavaScriptCore JIT activity involving rest-parameter spread arguments with out-of-bounds negative indices.
  • The exploit primitive leaks a controlled value (0x1234) from the stack via uninitialized variable access after JIT optimization. Heap spray or stack value patterns such as 0x1234 appearing as a return value from JIT-compiled rest-parameter access may indicate active exploitation.
  • ·The vulnerability affects WebKit as shipped in Safari 12.1.2 and earlier, iOS 12.4 and earlier, macOS Mojave 10.14.6 and earlier, tvOS 12.4, watchOS 5.3, iTunes for Windows 12.9.6, iCloud for Windows 7.13 and 10.6. Detection rules targeting DFGArgumentsEliminationPhase are only relevant to unpatched versions of these products.
  • ·The PoC requires JIT compilation to trigger (loop count ~1,000,000). Environments with JIT disabled (e.g., --no-jit or restricted sandbox configurations) will not be vulnerable to this specific code path.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.09.3CRITICALAV:N/AC:M/Au:N/C:C/I:C/A:C
osv8.8HIGH
vendor_debian8.8HIGH
vendor_redhat8.8HIGH
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