modules: add nft_catchall (CVE-2026-23111, nf_tables catch-all abort UAF)

The newest nftables LPE: a use-after-free in the nf_tables transaction-
abort path. An inverted condition (a stray '!') in
nft_map_catchall_activate() makes the abort path process active catch-all
map elements instead of skipping them; a catch-all GOTO element drives a
chain's use-count to zero so a following DELCHAIN frees it while the
catch-all verdict still references it -> UAF, escalatable from an
unprivileged user (userns + nftables) via modprobe_path/selinux_state ROP.
Fixed upstream by f41c5d1; CWE-416, CVSS 7.8; not in CISA KEV. Public
reproduction by FuzzingLabs.

Takes the corpus to 43 modules / 38 CVEs.

🟡 reconstructed trigger, primitive-only, NOT VM-verified — same contract
as nf_tables (CVE-2024-1086). detect() version-gates (catch-all elems
~5.13; Debian backports 6.1.164/6.12.73/6.18.10, 7.0+ inherits) AND
requires unprivileged user_ns clone (else PRECOND_FAIL). exploit() forks
an isolated child, builds a verdict map with a catch-all GOTO element,
provokes an aborting batch to drive the abort-path UAF, observes slabinfo,
and returns EXPLOIT_FAIL — the per-kernel leak + R/W + modprobe_path ROP
is not bundled. kernel_range table verified drift-clean against the live
Debian tracker (the 6.18 branch / 6.18.10 fix is the real forky/sid
backport; the earlier 7.0.10 figure was wrong).

Wired: registry, Makefile, safety rank (35), 6 detect() test rows (version
+ userns gating), CVE_METADATA.json + cve_metadata.c + KEV_CROSSREF.md
(sorted insert, CWE-416/T1068/not-KEV), README + CVES.md + website counts
(43/38) + yellow pill, RELEASE_NOTES v0.9.11, verify-vm target. Credit:
FuzzingLabs + upstream fix f41c5d1. Version 0.9.11.

tests/test_detect.c

@@ -71,6 +71,7 @@ extern const struct skeletonkey_module nft_pipapo_module;
 extern const struct skeletonkey_module ptrace_pidfd_module;
 extern const struct skeletonkey_module sudo_host_module;
 extern const struct skeletonkey_module cifswitch_module;
+extern const struct skeletonkey_module nft_catchall_module;
 
 static int g_pass = 0;
 static int g_fail = 0;
@@ -842,6 +843,54 @@ static void run_all(void)
 		SKELETONKEY_PRECOND_FAIL);
 	unsetenv("SKELETONKEY_CIFS_ASSUME_PRESENT");
 
+	/* ── nft_catchall (CVE-2026-23111) ───────────────────────────
+	 * Version-gated: predates-gate at catch-all set elements (~5.13),
+	 * then Debian backports 6.1.164 / 6.12.71 / 7.0.10, PLUS unprivileged
+	 * user_ns clone required (else PRECOND_FAIL). h_kernel_6_12 allows
+	 * userns; h_kernel_5_14_no_userns denies it. */
+
+	/* 5.12.50 predates catch-all set elements (~5.13) → OK */
+	struct skeletonkey_host h_nca_512 =
+		mk_host(h_kernel_6_12, 5, 12, 50, "5.12.50-test");
+	run_one("nft_catchall: 5.12.50 predates catch-all (~5.13) → OK",
+		&nft_catchall_module, &h_nca_512,
+		SKELETONKEY_OK);
+
+	/* 6.1.164 exact backport → OK via patch table */
+	struct skeletonkey_host h_nca_61164 =
+		mk_host(h_kernel_6_12, 6, 1, 164, "6.1.164-test");
+	run_one("nft_catchall: 6.1.164 (exact backport) → OK via patch table",
+		&nft_catchall_module, &h_nca_61164,
+		SKELETONKEY_OK);
+
+	/* 7.1.0 newer than every entry → mainline-inherited fix → OK */
+	struct skeletonkey_host h_nca_710 =
+		mk_host(h_kernel_6_12, 7, 1, 0, "7.1.0-test");
+	run_one("nft_catchall: 7.1.0 above all backports → OK (mainline inherit)",
+		&nft_catchall_module, &h_nca_710,
+		SKELETONKEY_OK);
+
+	/* 6.1.163 (one below the 6.1.164 backport) + userns → VULNERABLE */
+	struct skeletonkey_host h_nca_61163 =
+		mk_host(h_kernel_6_12, 6, 1, 163, "6.1.163-test");
+	run_one("nft_catchall: 6.1.163 + userns allowed → VULNERABLE",
+		&nft_catchall_module, &h_nca_61163,
+		SKELETONKEY_VULNERABLE);
+
+	/* 6.12.70 (one below the 6.12.71 backport) + userns → VULNERABLE */
+	struct skeletonkey_host h_nca_61270 =
+		mk_host(h_kernel_6_12, 6, 12, 70, "6.12.70-test");
+	run_one("nft_catchall: 6.12.70 + userns allowed → VULNERABLE",
+		&nft_catchall_module, &h_nca_61270,
+		SKELETONKEY_VULNERABLE);
+
+	/* same vulnerable kernel but unprivileged userns denied → PRECOND_FAIL */
+	struct skeletonkey_host h_nca_nouserns =
+		mk_host(h_kernel_5_14_no_userns, 6, 1, 163, "6.1.163-nouserns-test");
+	run_one("nft_catchall: 6.1.163 but userns denied → PRECOND_FAIL",
+		&nft_catchall_module, &h_nca_nouserns,
+		SKELETONKEY_PRECOND_FAIL);
+
 	/* ── coverage report ─────────────────────────────────────────
 	 * Iterate the runtime registry (populated by skeletonkey_register_*
 	 * calls in main()) and warn for any module that was not touched