KSM merges identical anonymous pages across processes. An attacker who can place chosen page-sized content in a victim's memory can detect the merge through the timing of the resulting copy-on-write fault, and so leak memory contents.
There is no upstream fix; removing the side channel means removing deduplication. Distribution trackers describe it the same way - Debian marks src:linux unfixed with "Inherent design limitation, can be avoided by not using KSM", Red Hat closed its bug WONTFIX, and Ubuntu records no upstream fix as of 2024-06-17: https://security-tracker.debian.org/tracker/CVE-2021-3714 https://bugzilla.redhat.com/show_bug.cgi?id=1931327 https://ubuntu.com/security/CVE-2021-3714 CC: Paul Barker <[email protected]> AI-Generated: Uses Claude (claude-opus-5) Signed-off-by: Junjie Cao <[email protected]> --- v4: - use the review's comment and status wording; drop the KSM runtime opt-in paragraph v3: https://lore.kernel.org/openembedded-core/[email protected]/ meta/recipes-kernel/linux/cve-exclusion.inc | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/meta/recipes-kernel/linux/cve-exclusion.inc b/meta/recipes-kernel/linux/cve-exclusion.inc index b2eb15d0..36643ccc 100644 --- a/meta/recipes-kernel/linux/cve-exclusion.inc +++ b/meta/recipes-kernel/linux/cve-exclusion.inc @@ -197,3 +197,12 @@ CVE_STATUS[CVE-2025-71145] = "cpe-stable-backport: Fixed from v6.18.3" # https://ubuntu.com/security/CVE-2019-14899 CVE_STATUS[CVE-2019-14899] = "unpatched: Consequence of the default weak host \ model, no upstream fix" + +# Triaged August 2026 - no upstream fix, Debian says "Inherent design +# limitation, can be avoided by not using KSM", Red Hat closed their bug as +# WONTFIX. +# https://security-tracker.debian.org/tracker/CVE-2021-3714 +# https://bugzilla.redhat.com/show_bug.cgi?id=1931327 +# https://ubuntu.com/security/CVE-2021-3714 +CVE_STATUS[CVE-2021-3714] = "unpatched: Timing side channel inherent to Kernel \ +Same-page Merging (KSM) page deduplication" -- 2.43.0
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