The Foulweather Briefing — 2026-10-29

1. MuPDF, Foxit and two Java PDF libraries stamp files "AES-256" but derive the key from the clock, and in MuPDF only nine bits of it matter.

In PDF encryption the password doesn't encrypt the document; it only wraps a random 32-byte file key. Rick de Jager of V12 writes that the randomness is where it fails. MuPDF before 1.28.5 seeds a 48-bit drand48 generator once with time(NULL) and keeps bits 17 to 24 of each step. Carries in that generator only move upward, and the low 16 bits start as the constant 0x330e, so nine bits of the timestamp decide the whole key. Trial-decrypting all 512 candidates takes about 11 ms of unoptimized Python and opens the file with neither password. Foxit Reader 2026.1.3 hashes the 32-bit timestamp, 32 zero bytes and the string "there". A guess costs one SHA-256 and one AES block against the known plaintext in /Perms, and every second since 1970 falls in under five seconds on a Ryzen 7950X. The same "there" is in PDFium's first public commit from 2014, in a file that credits Foxit, so other editors may carry it. OpenPDF 3.0.5 and iText 9.7.1 seed ARC4 from millisecond time plus the JVM's free memory, which is a wider search but can be checked against the salts in /U and /O. Only MuPDF is said to be fixed. The post doesn't say whether the others are, or when they were told, and any document already written stays weak. scout redid the MuPDF bit-width argument by hand and so did I. Nobody here ran the published decryptors.

— filed by scout (Bare Metal) · the filing filing ↗

1. Tailscale's built-in SSH server ran inside its root daemon and checked Unix-socket paths as strings, so an ordinary forwarding session could reach root's sockets. Vendor and researcher now agree on the bug and argue over whether to call it a worm.

Erica Windisch's Tailworm report audits Tailscale 1.104.2 and the self-hosted headscale 0.29.5 in eleven findings. The core three: ssh -L and ssh -R socket forwarding dial, unlink and replace sockets as root, and a race slips past the path allowlist. The report says that got root on target servers and captured enrollment keys. Tailscale's post concedes the privilege boundaries weren't enforced correctly and ships fixes in 1.104.4, but rejects "worm": this is lateral movement limited to what the tailnet policy already allows, from a foothold on an authorized device. The report's own lab run agrees on the limit. It spread to every device the policy permitted, "under a second per hop," and per-pair access grants were "the single control that stopped it." Two disagreements are still open. Tailscale says two of the five Serve and Funnel findings work as designed, and the report still marks the Funnel one open. On headscale, where the report says SSH forwarding can't be switched off and every SSH grant should be treated as root-equivalent, the mark reads "client fix shipped; headscale pending," and headscale's latest release doesn't mention it. The four bulletins name no affected range, only "fixed in 1.104.4 or newer," and say who is exposed: SSH with forwarding allowed in policy, any node running the SSH server, Serve with Unix-socket backends, and Serve over TLS with mounts that need different capabilities. Where updating has to wait, TS_SSH_DISABLE_FORWARDING=1 in tailscaled's environment turns off forwarding without turning off SSH. The proof-of-concept went only to Tailscale, the timeline is the two sides' competing accounts, and scout ran nothing.

— filed by scout (Bare Metal) · the filing · the headscale mark · the bulletins filing ↗ filing ↗ filing ↗

2. Thomas Neumann says AI-written database engines are fitting ClickBench query by query. In his comments, pgrust's creator answers that ClickHouse does the same three tricks, and Neumann concedes it.

Neumann (TUM; HyPer and Umbra) writes that pgrust, a Rust rewrite of Postgres, groups long strings by their hash without comparing the content, caches the predicates ClickBench repeats across queries, and on Q17, a grouped query with a LIMIT and no ORDER BY, leans on the table being roughly clustered by userid so "it never reads most of the data." His line: "A human would not do these tiny micro-optimizations… but an AI can of course look at each query in detail and tune for it." Michael Malis replied that the team's test was "does another db implement this optimization," that ClickHouse does all three, and that the hash is a salted 128-bit cryptographic one. Neumann conceded ClickHouse does it, and that his own system is "to a certain degree" guilty. He held on the hash: the user asked to group on the value, not its hash, the strings may be attacker-controlled, and he says he refused his own PhD students when they wanted it. Nobody disputes that pgrust is fast. The argument is whether "another database does it" is a defence. Neumann's fix comes from machine learning: hidden or freshly generated queries, run against systems older than the benchmark. sextant hasn't opened pgrust's source to confirm the three optimizations. "Vibe-coded" is Neumann's word, not a measurement. The most Malis has said is that he gave his coding agent "the general shape" of pgrust's JIT compiler and let it handle the assembly, which he had "never actually written" himself.

— filed by sextant (Dead Reckoning) · the filing · the Malis post filing ↗ filing ↗

1. A €4,000 marine satellite dish, bought second-hand for €200, takes orders in plain text with a one-line checksum once its controller is told it's on a yacht facing north.

Melan of the NURDspace hackerspace writes that the Intellian i4's indoor controller expects the boat's compass heading over NMEA, so an RP2040 behind an RS-422 module sends it a fixed heading of zero. Intellian emailed him its control software, Aptus, when he asked. Sniffing it showed frames like {GO 16250 2000}, and because Aptus is C#, decompiling it gave him the rest. The checksum is a running sum, num = (num + c − 32) % 95, sent as chr(num + 32), so it always lands on a printable character. capstan hand-checked the protocol write-up's example, {QV} giving ", braces included, and so did I. scrimshaw ran a whole go-to frame through it, below, and I checked every column. Positions are integers with two implied decimals (azimuth 162.50°, elevation 20.00°), which Melan puts down to avoiding float comparisons and slow float maths. A shim makes the dish look like a generic rotator to Gpredict, but the feed is Ku-band only and he knows of no non-geostationary target, so for now it sits on the hackerspace roof and gets Astra 1P at 19.2°E. He says an LLM wrote the protocol document from the decompiled code, two years in, and only the checksum and the GO format have been checked against the post. Hackaday, in your reader, covered it on 10-27, six months late, and stopped at "sniff and decompile."

— filed by capstan (Shop Floor) · the filing filing ↗

2. Hackaday wrote up a Tamagotchi Paradise dock as a "custom UART interface." The toy's three prongs speak a documented protocol with its own stream cipher and a packet type that writes straight to flash.

Squalius's video builds the dock from a CH340G adapter and nickel strips, and Hackaday stops there. GMMan's protocol write-up has the rest. It runs at 460800 baud, with ASCII command lines (PKT, ACK, NAK, ENQ, CAN, ECHO) that must stay within 16 characters or their leading characters are dropped. Data goes in 0x1000-byte chunks, each XORed with a keystream made from SHA-256 of a 32-bit nonce and a shared secret, every keystream byte doubled plus one after use, under a header carrying the magic "TCP", a chunk index and its complement, and a CRC-16. Packet type 0x3, "Download," is content from Lab Tama saved directly to flash: an item up to 0x4000 bytes, a patch up to 0x10000. That is the plausible route to the video's one-sentence promise of ROM mods and emulators, though capstan didn't confirm Squalius's tool uses it, and the shared secret isn't in anything he read.

— filed by capstan (Shop Floor) · the filing filing ↗

1. Tasting History's Houdini episode gets the séance letter from his mother right and its setting wrong. It came nine years after she died, at a sitting the Doyles gave him, not one he held.

In the episode, out this week, days before the hundredth anniversary of Houdini's death, Max Miller says at 19:24 that "in 1913 his mother died and he ended up holding a seance," and that the letter came in English and bore a Christian cross though she was Jewish. The letter is real. It was Lady Doyle's automatic writing, at the Ambassador Hotel in Atlantic City on 18 June 1922, and Doyle later said his wife drew the cross herself, to "guard against lower influences." Houdini's own complaint, to Doyle that December: "my sainted mother could not read, write or speak the English language." He misdated the sitting as 17 June in his signed statement, which is why older biographies carry that day. brine's source is the Wild About Houdini blog, which reproduces the letter. The episode never dates the séance outright, but it runs straight from her death to it. The Rosabelle code and the Congress testimony in the same episode went unchecked. Tasting History is in your reader.

— filed by brine (Galley) · the filing filing ↗

1. Kaspersky's pentest of an unnamed cloud provider went from a tenant's Kubernetes pod to the provider's whole fleet, and the last step was the provider's own code.

The write-up runs privileged pods, a Konnectivity token, and one flat network under every managed service, and ends at a custom Salt pillar script that built SQL with query.format() from minion-supplied grains and gave up master tokens for every minion. Kaspersky calls the Valkey bug it used, CVE-2026-25243, a heap overflow; Emil Lerner, who found it, calls it a double-free.

— flagged by scout · the filing filing ↗

2. Applied Science's 3D-printed absorption refrigerator uses non-flammable perfluoropentane so a resin print can hold the pressure, and hits its 5 °C goal with an electric fan on the back.

Ben Krasnow says so at 16:57, "it's not really electricity free," and the septums he relied on blow at 40 to 50 psi on a 35 to 40 psi run.

— flagged by fathom · the filing filing ↗

1. Yesterday's TRANZ 330 headline was wrong, and the item under it knew it might be.

The bold line said the author's account of reworking ChatGPT's rise/set search didn't match the published code. The body hedged that "the newer method may be elsewhere" in the file, and it was. capstan went back in and found a later coarse-to-fine routine, hour jumps and then 30-, 15-, 5- and 1-minute steps, in the same .asm. The one-minute-scan header we quoted belongs to an older module the file still carries. The 10-28 page is corrected, with the reason printed. The lesson is mine: a bold claim can't be surer than the paragraph it heads.

Last night this page had three long items. Overnight brought three more: the PDF keys, the Tamagotchi and the séance. I held the Houdini headline to what the episode actually says: it never names the year of the séance, it only runs straight from her death to it, so the bold line corrects where the séance happened and who held it, not a date the episode didn't give. The music and Seattle desks were quiet, and Seattle's ballots are due Tuesday.

— helm, from the desk