cbcvebase.
CVE-2019-8558
published 2019-12-18

CVE-2019-8558: Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in iOS 12.2, tvOS 12.2, watchOS 5.2, Safari 12.1, iTunes…

PriorityP263high8.8CVSS 3.1
AVNACLPRNUIRSUCHIHAH
EXPLOIT
EPSS
7.47%
93.8th percentile
Multiple memory corruption issues were addressed with improved memory handling. This issue is fixed in iOS 12.2, tvOS 12.2, watchOS 5.2, Safari 12.1, iTunes 12.9.4 for Windows, iCloud for Windows 7.11. Processing maliciously crafted web content may lead to arbitrary code execution.

Affected

19 ranges
VendorProductVersion rangeFixed in
appleicloud< 7.117.11
appleicloud_for_windows
appleicloud_for_windows>= unspecified < iCloud for Windows 7.11iCloud for Windows 7.11
appleios
appleios>= unspecified < iOS 12.2iOS 12.2
appleiphone_os< 12.212.2
appleitunes< 12.9.412.9.4
appleitunes_12.9.4_for_windows
appleitunes_for_windows>= unspecified < iTunes 12.9.4 for WindowsiTunes 12.9.4 for Windows
applesafari< 12.112.1
applesafari
applesafari>= unspecified < Safari 12.1Safari 12.1
appletvos< 12.212.2
appletvos
appletvos>= unspecified < tvOS 12.2tvOS 12.2
applewatchos< 5.25.2
applewatchos
applewatchos>= unspecified < watchOS 5.2watchOS 5.2
debianwebkit2gtk< webkit2gtk 2.24.1-1 (bookworm)webkit2gtk 2.24.1-1 (bookworm)

Detection & IOCsextracted from sources · hover to see the quote

  • PoC JavaScript hallmark: allocation of a large Float64Array (size 65493) inside a for-in loop over a 4-element float array, combined with a bare RegExp() call — this specific pattern is the GC-trigger sequence used to free the jettisoned CodeBlock.
  • ·The exploit PoC targets JavaScriptCore (jsc) at 'current HEAD and release' at time of disclosure (early 2019); the crash is reproducible in debug builds where freed memory is overwritten with poison value 0xbadbeef0 — release builds may not exhibit the same crash address.
  • ·The use-after-free is only reachable via the specific code path where JITCode is kept alive at CachedCall::call entrypoint for the duration of a callback, preventing Watchpoint cleanup on CodeBlock destruction — this path may not be triggered by all JS engines or all WebKit configurations.

CVSS provenance

nvdv3.18.8HIGHCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
nvdv2.06.8MEDIUMAV:N/AC:M/Au:N/C:P/I:P/A:P
osv8.8HIGH
vendor_debian8.8HIGH
vendor_redhat8.8HIGH
CVEs like this are exactly what “Exploited This Week” covers.

Every Monday: what got weaponized or added to CISA KEV in the last seven days — each CVE cross-linked to its PoC, Nuclei template, and detection rule. Free, one email a week, unsubscribe in one click.