modules: add cifswitch (CVE-2026-46243, Asim Manizada's CIFSwitch)

CIFSwitch is the newest kernel-7-era LPE not already in the corpus: a
~19-year-old logic flaw in fs/smb/client/cifs_spnego.c where the
cifs.spnego request-key type accepts key descriptions created by
userspace (add_key(2)/request_key(2)) without verifying the request came
from the in-kernel CIFS client. The description's authority-bearing
fields (pid/uid/creduid/upcall_target) are trusted by the root cifs.upcall
helper; with user+mount namespace tricks an unprivileged user coerces
cifs.upcall into loading an attacker NSS module as root. Fixed upstream by
3da1fdf4efbc (merged 7.1-rc5); CWE-20; not in CISA KEV.

Takes the corpus to 42 modules / 37 CVEs.

🟡 honest port — full chain not VM-verified. detect() gates on the kernel
version (Debian backports 5.10.257/6.1.174/6.12.90/7.0.10) AND on the
cifs userspace path (cifs.upcall / cifs.spnego request-key rule), so a
vulnerable kernel without cifs-utils is PRECOND_FAIL not a false positive
(override via SKELETONKEY_CIFS_ASSUME_PRESENT=1/0). exploit() fires only
the non-destructive add_key(2) cifs.spnego probe (no upcall, loads
nothing, revoked immediately) and returns EXPLOIT_FAIL without a euid-0
witness — the namespace+NSS root-pop is not bundled until VM-verified.
--mitigate blocklists the cifs module; --cleanup reverts.

Wired everywhere: registry, Makefile, safety rank (86), 6 detect() test
rows (env-driven precondition override), CVE_METADATA.json + cve_metadata.c
+ KEV_CROSSREF.md (sorted insert, CWE-20/T1068/not-KEV), README + CVES.md
+ website counts (42/37) and a yellow module pill, RELEASE_NOTES v0.9.10,
verify-vm target (sweep pending). Credit: Asim Manizada. Version 0.9.10.

Makefile

@@ -232,6 +232,11 @@ SUH_DIR  := modules/sudo_host_cve_2025_32462
 SUH_SRCS := $(SUH_DIR)/skeletonkey_modules.c
 SUH_OBJS := $(patsubst %.c,$(BUILD)/%.o,$(SUH_SRCS))
 
+# CVE-2026-46243 CIFSwitch — cifs.spnego userspace-forged key trust (Asim Manizada)
+CIW_DIR  := modules/cifswitch_cve_2026_46243
+CIW_SRCS := $(CIW_DIR)/skeletonkey_modules.c
+CIW_OBJS := $(patsubst %.c,$(BUILD)/%.o,$(CIW_SRCS))
+
 # Top-level dispatcher
 TOP_OBJ  := $(BUILD)/skeletonkey.o
 
@@ -245,7 +250,7 @@ MODULE_OBJS := $(CFF_OBJS) $(DP_OBJS) $(EB_OBJS) $(PK_OBJS) $(NFT_OBJS) \
                $(DDC_OBJS) $(FGN_OBJS) $(P2TR_OBJS) \
                $(SCHW_OBJS) $(UDB_OBJS) $(PTH_OBJS) \
                $(MUT_OBJS) $(SRN_OBJS) $(TIO_OBJS) $(VSK_OBJS) $(PIP_OBJS) \
-               $(PPF_OBJS) $(SUH_OBJS)
+               $(PPF_OBJS) $(SUH_OBJS) $(CIW_OBJS)
 
 ALL_OBJS := $(TOP_OBJ) $(CORE_OBJS) $(REGISTRY_ALL_OBJ) $(MODULE_OBJS)