[OE-core][PATCH v4 8/8] cve-exclusions: set status for CVE-2023-6240

[Junjie Cao <junjie.cao@linux.dev>]

"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 <paul@pbarker.dev>
AI-Generated: Uses Claude (claude-opus-5)
Signed-off-by: Junjie Cao <junjie.cao@linux.dev>
---
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/20260812072842.1176341-1-junjie.cao@linux.dev/

 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@@ -250,3 +250,13 @@ CVE_STATUS[CVE-2023-3397] = "unpatched: Proposed fix was withdrawn"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/20231016060519.231880-1-joshi.k@samsung.com/
 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