CVE-2020-15999

Google Chrome bundles the open-source FreeType library for font rendering, and that library contains a heap buffer overflow (CWE-787, out-of-bounds write) in its Load_SBit_Png function. The flaw is triggered when the browser loads a crafted font containing a malicious PNG image embedded as embedded bitmap data, typically from a web page the victim visits, corrupting heap memory with attacker-controlled data. Successful exploitation can crash the browser or execute code in the renderer, and it was used in the wild as part of an exploit chain combined with CVE-2020-17087 (Windows kernel) and CVE-2020-16010 (Android) to escape the sandbox. Anyone running an affected Google Chrome release that ships the vulnerable FreeType code, across Windows, macOS, Linux, Chrome OS and Android, is affected, meaning effectively the entire Chrome install base at the time of disclosure. The vulnerability is confirmed exploited in the wild (listed in CISA's KEV catalog, added 2021-11-03; ransomware use unknown), Google patched it in Chrome 86.0.4240.111, no public proof-of-concept is known, and EPSS estimates a 44.3% probability of exploitation within 30 days (99th percentile).

What to do: Update Google Chrome to 86.0.4240.111 or later (any current stable-channel release satisfies this), and where other software bundles FreeType directly, update to FreeType 2.10.4 or later per the upstream fix. Because the bug was chained with CVE-2020-17087 on Windows and CVE-2020-16010 on Android, also apply the corresponding Microsoft Windows and Android updates to close the sandbox-escape chain. Use endpoint management to inventory browser versions and confirm no endpoints remain below the fixed release, as required by the CISA KEV catalog.