"Marvin" is Hubert Kario's Bleichenbacher-style timing oracle research:
https://people.redhat.com/~hkario/marvin/ The affected code is the generic software RSA PKCS#1 v1.5 unpadding in crypto/rsa-pkcs1pad.c. pkcs1pad_decrypt_complete() has three secret-dependent early exits (leading zero byte, block type, minimum padding length) and a loop whose trip count depends on the position of the separator, so the time taken reveals padding validity. There is no constant-time unpadding or implicit-rejection fallback in the tree. Red Hat classifies it CWE-203 and has shipped fixes only in RHEL errata (RHSA-2024:2758, RHSA-2024:3618 and others); the bugzilla is still NEW. Ubuntu records "appears unfixed in upstream as of 2024.08.24" and Debian lists src:linux vulnerable in all suites: https://access.redhat.com/security/cve/CVE-2023-6240 https://ubuntu.com/security/CVE-2023-6240 https://security-tracker.debian.org/tracker/CVE-2023-6240 CC: Paul Barker <[email protected]> AI-Generated: Uses Claude (claude-opus-5) Signed-off-by: Junjie Cao <[email protected]> --- v4: - drop the practical-exposure paragraph; use the review's comment and status wording - quote Ubuntu's note verbatim v3: https://lore.kernel.org/openembedded-core/[email protected]/ meta/recipes-kernel/linux/cve-exclusion.inc | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/meta/recipes-kernel/linux/cve-exclusion.inc b/meta/recipes-kernel/linux/cve-exclusion.inc index 4729191a..8714173c 100644 --- a/meta/recipes-kernel/linux/cve-exclusion.inc +++ b/meta/recipes-kernel/linux/cve-exclusion.inc @@ -250,3 +250,13 @@ CVE_STATUS[CVE-2023-3397] = "unpatched: Proposed fix was withdrawn" # https://ubuntu.com/security/CVE-2023-6238 # https://lore.kernel.org/linux-nvme/[email protected]/ CVE_STATUS[CVE-2023-6238] = "unpatched: Proposed fix was not merged" + +# Triaged August 2026 - "Marvin" attack, Red Hat reports this fixed but the +# exact patch is unidentified (see RHSA-2024:2758, RHSA-2024:3618 & others). +# Unfixed in Debian, "Needs evaluation" in Ubuntu. +# https://people.redhat.com/~hkario/marvin/ +# https://access.redhat.com/security/cve/cve-2023-6240 +# https://security-tracker.debian.org/tracker/CVE-2023-6240 +# https://ubuntu.com/security/CVE-2023-6240 +CVE_STATUS[CVE-2023-6240] = "unpatched: Fixed in RHEL but patch not identified \ +publicly" -- 2.43.0
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