CVE-2015-2877

Name	CVE-2015-2877
Description	Kernel Samepage Merging (KSM) in the Linux kernel 2.6.32 through 4.x does not prevent use of a write-timing side channel, which allows guest OS users to defeat the ASLR protection mechanism on other guest OS instances via a Cross-VM ASL INtrospection (CAIN) attack. NOTE: the vendor states "Basically if you care about this attack vector, disable deduplication." Share-until-written approaches for memory conservation among mutually untrusting tenants are inherently detectable for information disclosure, and can be classified as potentially misunderstood behaviors rather than vulnerabilities
Source	CVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
linux (PTS)	jessie, jessie (lts)	3.16.84-1	vulnerable
	stretch (security)	4.9.320-2	vulnerable
	stretch (lts), stretch	4.9.320-3	vulnerable
	buster (security), buster, buster (lts)	4.19.316-1	vulnerable
	bullseye	5.10.223-1	vulnerable
	bullseye (security)	5.10.226-1	vulnerable
	bookworm	6.1.115-1	vulnerable
	bookworm (security)	6.1.119-1	vulnerable
	trixie	6.12.5-1	vulnerable
	sid	6.12.6-1	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
linux	source	(unstable)	(unfixed)	unimportant
linux-2.6	source	(unstable)	(unfixed)	unimportant

Notes

https://www.usenix.org/conference/woot15/workshop-program/presentation/barresi
http://www.antoniobarresi.com/security/cloud/2015/07/30/cain/
Architectual limitation, workaround exists