modules: add ptrace_pidfd (CVE-2026-46333, Qualys ptrace/pidfd_getfd cred-steal)

New module for Qualys's 2026-05-20 disclosure: a __ptrace_may_access logic flaw leaves a process dropping privileges briefly reachable past its dumpable boundary; pidfd_getfd(2) steals root-opened fds / authenticated channels from it. Default-distro, no userns, arch-agnostic (fd-steal, no shellcode).

detect(): version-pinned, predates-gate at pidfd_getfd's 5.6 introduction; kernel_range from Debian backports (5.10.251/6.1.172/6.12.88/7.0.7), drift-check clean. exploit(): spawns a setuid victim, pidfd_open()s it, sweeps pidfd_getfd() over its fd table during the cred-drop window, reports any uid-0-owned fd captured from a non-root context. Honest EXPLOIT_FAIL without a euid-0 witness; not yet VM-verified. mitigate(): yama ptrace_scope=2; cleanup() reverts. auditd/sigma/falco rules, NOTICE.md (Qualys TRU credit) + MODULE.md, safety rank 84.

Wiring: registry, Makefile, cve_metadata (+JSON source), verify-vm/targets.yaml (ubuntu2204 + mainline 5.15.5 target, sweep pending). Docs: README + CVES.md + docs/index.html counts 39->40 modules / 34->35 CVEs; added to not-yet-verified lists + corpus pill.

CVES.md

@@ -23,16 +23,16 @@ Status legend:
 - 🔴 **DEPRECATED** — fully patched everywhere relevant; kept for
   historical reference only
 
-**Counts:** 39 modules total covering 34 CVEs; **28 of 34 CVEs
+**Counts:** 40 modules total covering 35 CVEs; **28 of 35 CVEs
 verified end-to-end in real VMs** via `tools/verify-vm/`. 🔵 0 · ⚪ 0
 planned-with-stub · 🔴 0. (One ⚪ row below — CVE-2026-31402 — is a
 *candidate* with no module, not counted as a module.)
 
 > **Note on unverified rows:** `vmwgfx` / `dirty_cow` /
-> `mutagen_astronomy` / `pintheft` / `vsock_uaf` / `fragnesia` are
-> blocked by their target environment (VMware-only, kernel < 4.4,
-> mainline panic, kmod not autoloaded, or t64-transition libs),
-> not by missing code. See
+> `mutagen_astronomy` / `pintheft` / `vsock_uaf` / `fragnesia` /
+> `ptrace_pidfd` are blocked by their target environment (VMware-only,
+> kernel < 4.4, mainline panic, kmod not autoloaded, t64-transition
+> libs) or are brand-new this cycle, not by missing code. See
 > [`tools/verify-vm/targets.yaml`](tools/verify-vm/targets.yaml).
 >
 > All three now have **pinned fix commits and version-based
@@ -93,6 +93,7 @@ root on a host can upstream their kernel's offsets via PR.
 | CVE-2026-31635 | DirtyDecrypt / DirtyCBC — rxgk missing-COW in-place decrypt | LPE (page-cache write into a setuid binary) | mainline Linux 7.0 (commit `a2567217ade970ecc458144b6be469bc015b23e5`) | `dirtydecrypt` | 🟡 | **Ported from the public V12 PoC, exploit body not yet VM-verified.** Sibling of Copy Fail / Dirty Frag in the rxgk (AFS rxrpc encryption) subsystem. `fire()` sliding-window page-cache write, ~256 fires/byte; rewrites the first 120 bytes of `/usr/bin/su` with a setuid-shell ELF. detect() is version-pinned: kernels < 7.0 predate the vulnerable rxgk code (Debian: `<not-affected, vulnerable code not present>` for 5.10/6.1/6.12); kernels ≥ 7.0 have the fix. `--active` probe fires the primitive at a `/tmp` sentinel for empirical override. x86_64. |
 | CVE-2026-46300 | Fragnesia — XFRM ESP-in-TCP `skb_try_coalesce` SHARED_FRAG loss | LPE (page-cache write into a setuid binary) | mainline 7.0.9; older Debian-stable branches still unfixed as of 2026-05-22 | `fragnesia` | 🟡 | **Ported from the public V12 PoC, exploit body not yet VM-verified.** Latent bug exposed by the Dirty Frag fix (`f4c50a4034e6`). AF_ALG GCM keystream table + userns/netns + XFRM ESP-in-TCP splice trigger pair; rewrites the first 192 bytes of `/usr/bin/su`. Needs `CONFIG_INET_ESPINTCP` + unprivileged userns (the in-scope question the old `_stubs/fragnesia_TBD` raised — resolved: ships, reports PRECOND_FAIL when the userns gate is closed). detect() is version-pinned at 7.0.9; older branches that haven't backported yet are flagged VULNERABLE on the version check (override empirically via `--active`). PoC's ANSI TUI dropped in the port. x86_64. |
 | CVE-2026-41651 | Pack2TheRoot — PackageKit `InstallFiles` TOCTOU | LPE (userspace D-Bus daemon → `.deb` postinst as root) | PackageKit 1.3.5 (commit `76cfb675`, 2026-04-22) | `pack2theroot` | 🟡 | **Ported from the public Vozec PoC, not yet VM-verified.** Two back-to-back `InstallFiles` D-Bus calls — first `SIMULATE` (polkit bypass + queues a GLib idle), then immediately `NONE` + malicious `.deb` (overwrites the cached flags before the idle fires). GLib priority ordering makes the overwrite deterministic, not a race. Disclosure by **Deutsche Telekom security**. Affects PackageKit 1.0.2 → 1.3.4 — default-enabled on Ubuntu Desktop, Debian, Fedora, Rocky/RHEL via Cockpit. `detect()` reads `VersionMajor/Minor/Micro` over D-Bus → high-confidence verdict (vs. precondition-only for dirtydecrypt/fragnesia). Debian-family only (PoC's built-in `.deb` builder). Needs `libglib2.0-dev` at build time; Makefile autodetects via `pkg-config gio-2.0` and falls through to a stub when absent. |
+| CVE-2026-46333 | ptrace `__ptrace_may_access` dumpable-race → `pidfd_getfd` credential-fd theft | LPE (steal a root-opened fd / authenticated channel from a process dropping privileges) | mainline 2026-05-14 (Debian backports 5.10.251 / 6.1.172 / 6.12.88 / 7.0.7) | `ptrace_pidfd` | 🟡 | **Qualys TRU disclosure (2026-05-20), exploit not yet VM-verified.** The `__ptrace_may_access` logic flaw leaves a process *dropping* privileges briefly reachable past its `dumpable` boundary; `pidfd_getfd(2)` rides that window. detect() is version-pinned with a predates-gate at `pidfd_getfd`'s 5.6 introduction. exploit() spawns a setuid victim (chage / pkexec / ssh-keysign), `pidfd_open()`s it and sweeps `pidfd_getfd()` across its descriptor table during the credential-drop window, reporting any uid-0-owned fd captured from a non-root context — honest `EXPLOIT_FAIL` without a euid-0 witness; the target-specific full root-pop is not bundled until VM-verified. Arch-agnostic (descriptor theft, no shellcode). `--mitigate` sets `kernel.yama.ptrace_scope=2`; `--cleanup` reverts it. Credit: Qualys TRU. |
 
 ## Operations supported per module
 
@@ -131,6 +132,7 @@ Symbols: ✓ = supported, — = not applicable / no automated path.
 | dirtydecrypt | ✓ (+ `--active`) | ✓ (ported) | — (upgrade kernel) | ✓ (evict page cache) | ✓ (auditd + sigma) |
 | fragnesia | ✓ (+ `--active`) | ✓ (ported) | — (upgrade kernel) | ✓ (evict page cache) | ✓ (auditd + sigma) |
 | pack2theroot | ✓ (PK version via D-Bus) | ✓ (ported) | — (upgrade PackageKit ≥ 1.3.5) | ✓ (rm /tmp + `dpkg -r`) | ✓ (auditd + sigma) |
+| ptrace_pidfd | ✓ | ✓ (primitive) | ✓ (yama ptrace_scope=2) | ✓ (restore ptrace_scope) | ✓ (auditd + sigma + falco) |
 
 ## Pipeline for additions