An issue was discovered in Xen through 4.14.x. There is a lack of preemption in evtchn_reset() / evtchn_destroy(). In particular, the FIFO event channel model allows guests to have a large number of event channels active at a time. Closing all of these (when resetting all event channels or when cleaning up after the guest) may take extended periods of time. So far, there was no arrangement for preemption at suitable intervals, allowing a CPU to spend an almost unbounded amount of time in the processing of these operations. Malicious or buggy guest kernels can mount a Denial of Service (DoS) attack affecting the entire system. All Xen versions are vulnerable in principle. Whether versions 4.3 and older are vulnerable depends on underlying hardware characteristics.

An issue was discovered in Xen through 4.14.x. Out of bounds event channels are available to 32-bit x86 domains. The so called 2-level event channel model imposes different limits on the number of usable event channels for 32-bit x86 domains vs 64-bit or Arm (either bitness) ones. 32-bit x86 domains can use only 1023 channels, due to limited space in their shared (between guest and Xen) information structure, whereas all other domains can use up to 4095 in this model. The recording of the respective limit during domain initialization, however, has occurred at a time where domains are still deemed to be 64-bit ones, prior to actually honoring respective domain properties. At the point domains get recognized as 32-bit ones, the limit didn't get updated accordingly. Due to this misbehavior in Xen, 32-bit domains (including Domain 0) servicing other domains may observe event channel allocations to succeed when they should really fail. Subsequent use of such event channels would then possi…

An issue was discovered in Xen through 4.14.x. The PCI passthrough code improperly uses register data. Code paths in Xen's MSI handling have been identified that act on unsanitized values read back from device hardware registers. While devices strictly compliant with PCI specifications shouldn't be able to affect these registers, experience shows that it's very common for devices to have out-of-spec "backdoor" operations that can affect the result of these reads. A not fully trusted guest may be able to crash Xen, leading to a Denial of Service (DoS) for the entire system. Privilege escalation and information leaks cannot be excluded. All versions of Xen supporting PCI passthrough are affected. Only x86 systems are vulnerable. Arm systems are not vulnerable. Only guests with passed through PCI devices may be able to leverage the vulnerability. Only systems passing through devices with out-of-spec ("backdoor") functionality can cause issues. Experience shows that such out-of-spec funct…

Insufficient policy enforcement in intent handling in Google Chrome on Android prior to 85.0.4183.83 allowed a remote attacker to obtain potentially sensitive information from disk via a crafted HTML page.

Heap buffer overflow in SwiftShader in Google Chrome prior to 84.0.4147.135 allowed a remote attacker to potentially exploit heap corruption via a crafted HTML page.

Race in Mojo in Google Chrome prior to 85.0.4183.102 allowed a remote attacker who had compromised the renderer process to potentially perform a sandbox escape via a crafted HTML page.

Inappropriate implementation in Content Security Policy in Google Chrome prior to 85.0.4183.83 allowed a remote attacker to leak cross-origin data via a crafted HTML page.

Insufficient policy enforcement in iOSWeb in Google Chrome on iOS prior to 85.0.4183.83 allowed a remote attacker to bypass navigation restrictions via a crafted HTML page.

Integer overflow in WebUSB in Google Chrome prior to 85.0.4183.83 allowed a remote attacker who had compromised the renderer process to potentially exploit heap corruption via a crafted HTML page.

Inappropriate implementation in Omnibox in Google Chrome on iOS prior to 85.0.4183.83 allowed a remote attacker to spoof the contents of the Omnibox (URL bar) via a crafted HTML page.