Security audit 2026-10-17, finding W1, stage 1. HandleDomainDMARC took any
address validate.Email takes; AllowedRecipients opened every stored address
on the hostname, not only the domain's hosted one; checkReportDomain
cross-checked the claimed domain only against a dmarc-reports+<tag> local
part. So a domain user of tenant A could store ops@<hostname> and from then
on anyone could mail a report claiming tenant B's domain to it, stored and
shown under B and counted toward B's 500; or store B's hosted address and
open B's mailbox without B choosing hosted. TestAllowedRecipients asserted
ops@<host> was allowed - a choice, now reversed.
Now: a custom address on the hostname is refused on the form ("choose
SelfPost hosted"); AllowedRecipients adds a domain's address only when it
is that domain's own hosted address; checkReportDomain requires a tag and
the claimed domain to equal it. The live registry (checked 2026-10-17)
holds two hosted addresses and no custom one on the hostname, so nothing
there changes.
Tests: TestCustomReportAddressOnTheHostnameIsRefused (typed, another
domain's hosted, the domain's own hosted typed as custom; an address
elsewhere still saves); TestAllowedRecipientsFollowTheDomainAddresses
inverted plus another domain's hosted address stored; untagged addresses
rejected in TestIngestMessageRejectsTagMismatch; the ingest tests deliver
to tagged addresses.
Docs: security.md § Accepted risks (DMARC), guide § DMARC reports;
CHANGELOG; plan.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding M3, stage 1. inboundSession.RcptTo
appended every RCPT (the outbound session de-duplicates), and the end of
the message inserted a row per recipient one statement at a time inside
Postfix's callback; the cut to 10 000 rows every 500 counted only the log
tailer's rows. Postfix accepts a repeated recipient up to
smtpd_recipient_limit (1 000) and sends each to the milter, so one message
was a thousand rows, uncut until the six-hourly prune.
Now: the inbound milter folds a repeated recipient (case-insensitive, as
cleanup's been_here() with BH_FLAG_FOLD does, and as session.RcptTo does);
a message's rows go in one transaction (store.InsertInboundSpamMessage,
which replaces InsertInboundSpam in milter.InboundStore); the count and the
cut moved from the tailer into the store (countInboundWrites, an atomic
counter on Store) so the milter's rows, the tailer's and the tailer's
start-up re-reads all count. store.InboundSpamLogMaxRows is the one cap.
Tests: TestInboundRecipientRepeatedIsOneRow (1 000 RCPT in two cases, one
row); TestInboundJournalIsCutWhicheverWriterWrites (a small cap: a message's
rows and refusals together cross the mark, the table is cut); the tailer's
own counting test went with its counter. go test ./internal/store
./internal/milter ./internal/logtail (Windows-only Follow failures aside).
Also gofmt of a test line from the M2 commit.
Docs: security.md § Mail path, architecture.md; CHANGELOG; plan.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding M1, stage 1. overLimit took
domainOf(MAIL FROM) whatever the login, and MailFrom ran it with an empty
login: with smtpd_delay_reject at its default Postfix runs no sender
restriction at MAIL and sends the milter's MAIL event at once, so a
stranger on 465/587 with no AUTH, or another tenant's application, could
name a victim domain in MAIL FROM and take its slots for the 10-minute
in-flight TTL, get the victim's application answered 451, and have a limit
row (and the "a rate limit is refusing mail" notification) written under
the victim's domain.
Now overLimit returns at once without a login and takes the domain from
ApplicationByLogin (loginDomain, fail-open like the rest); recordRejected's
Domain is the login's too. The send log already counts a domain's messages
by the login's domain (store.CountMessages, loginDomainID), so the limit
and the count now agree. The null-sender special case is gone: every
message is held to its login's domain.
Tests: TestRateLimitIsNotReservedByAnotherSendersMailFrom (a stranger with
no login; another tenant's application) - fails on the old code at the
second MAIL FROM; the domain-limit tests sign in as app1 at example.com.
e2e domain_limit_not_reserved_by_a_stranger: a domain with a limit of one,
three unauthenticated MAIL FROM naming it on 465, then its own message
passes and its second is refused 451.
Docs: security.md § Mail path; CHANGELOG; plan.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding X1, stage 0: the supported-versions
table named 1.x while the product is at 2.14 - an operator would have
read 2.x as unsupported. Latest 2.x yes, earlier 2.x and 1.x no.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding S6 (low), stage 0 - proven from
outside: `ETRN <an inbound domain>` on port 25 answered "250 Queuing
started". smtpd_etrn_restrictions was empty (Postfix allows every client)
and fast_flush_domains = $relay_domains, so a stranger could flush the
deferred queue toward an inbound domain's upstream at will. Now
smtpd_etrn_restrictions=reject (etrn_cmd -> smtpd_check_etrn -> reject_code
554, Postfix 3.10.13 src/smtpd/smtpd.c) and smtpd_discard_ehlo_keywords=etrn.
e2e: testInboundRelay sends EHLO + ETRN for the inbound domain on port 25
and expects 554 and no ETRN in the EHLO reply (etrnPort25);
checkPostfixHardening reads both settings back. To be run on the server.
Docs: architecture.md § Postfix; CHANGELOG; plan.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding A4 (low), stage 0. The line logged when
a request carries two unprefixed session cookies printed r.URL.Path raw,
so GET /confirm/<token> wrote the token to the log (reachable only with
PANEL_COOKIE_SECURE=false, where a sibling host can plant the bare name).
loggedPath moves from internal/web to internal/web/auth as LoggedPath
(web imports auth, not the other way) and both lines - the origin check's
refusal and the duplicate-cookie one - go through it.
Tests: TestDuplicateCookieLineHidesALinksToken; TestLoggedPathHidesTokens
moved with the function. go test ./internal/web ./internal/web/auth.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding M5 (low), stage 0. senderSession.Header
appended every From:/Sender: value; Postfix bounds one header at 60 000
bytes but not their number, and the signer's 1 MiB cap runs after the
sender check, so an application could make it hold megabytes per
connection (the reader's test: a hundred lines, 6 MB). judge needs only
none / one / more, so two of each are kept; the refusal text joins what is
kept, as before.
Tests: "a hundred From: lines" in the judgement table (refused, more than
one From: line); TestSenderKeepsTwoFromAndSenderLines. go test
./internal/milter.
Docs: security.md (the sentence "a few headers each"); CHANGELOG; plan.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding M2, stage 0 - proven on the live server:
Postfix quotes a refused recipient in its reply in internal form (quotes
removed, "; < > =" kept: extract_addr, tok822_internalize), so
RCPT TO:<"; from=<ceo@…> to=<board@…> proto=ESMTP helo=<x>; "@domain>
spelled a whole tail inside the reply, and inboundRejectRe, whose reply
ended at the FIRST "; from=<", took the stranger's sender, recipient and
inbound domain for the row.
Now the reply is greedy and the tail anchored: "; from=<…> to=<…>
proto=\S+", a HELO name holding none of Postfix's NEUTER_CHARACTERS
(smtpd.c:1634, helo_cmd neuters ` <>()\";@`), and one-word SASL fields to
the end of the line (a `.*` SASL tail would have let a quoted MAIL FROM
spell the whole tail). Belt and braces: a reply that still holds
"; from=<" - a line with two tails - makes no row, so neither a recipient
nor an un-neutered HELO name can choose one. The quote/bracket/space
filter on from/to stays.
Tests: TestInboundRecipientCannotWriteTheRow (the live line's shape, and
with a forged MAIL FROM too); TestInboundHeloCannotWriteTheRow now feeds
HELO names as Postfix logs them (neutered) and expects no row for the
un-neutered ones. go test ./internal/logtail on Windows (the three known
Windows-only Follow failures aside).
Docs: security.md § Mail path; CHANGELOG; plan line ticked.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding I2 (= M4), stage 0. drop_links listed
the outbound maps, sasldb2, the key tree and mail.log but not the three
DMARC maps that postfix-config.sh creates as root with `[ -e ] || : >`
when DMARC_REPORTS_ENABLE=true; -e is false for a dangling link and the
redirect follows it, and /data/postfix is the panel's. Now the three are in
drop_links, and both map loops refuse to create through a link
(`[ -e ] || [ -L ] || : >`).
e2e: TestStartsOnA28Data plants a dangling /data/postfix/dmarc_transport
with DMARC reports on and expects the "removing the symbolic link" line,
no file at the link's target, and a regular map. To be run on the server
with the stage.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Security audit 2026-10-17, finding A2 (high), stage 0; the mockup is
2c27275. A stolen global session could set its own password on the user
form - no current password asked, the session kept - and then pass the
backup's reauth with it, or add a second global user with a known
password. Now the user form calls reauth (the backup's check: bcrypt
against the signed-in user's own hash, under auth.AllowPasswordChange) when
it adds a user and when a save sets a password, changes the e-mail (reset
links go there) or changes the role, the own account included; deleting a
user asks too, refused on its own confirmation page (renderUserDelete, a
Flash on UserDelete). Name and reach alone are not asked. Missing or wrong:
401 on the same page, "Your account password is incorrect.", nothing saved.
Tests: TestUserFormAsksForTheAccountPassword (create, each of password,
e-mail, role, own password, reach alone, delete); the user-form tests send
the field (withAccountPassword gives root a real hash and h an auth
module). go vet, go test ./internal/web/... on Windows.
Docs: security.md § Backup and domain export, guide § Users, help word for
word with the mockup; CHANGELOG [Unreleased] Security; plan line ticked.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Full security audit at 44bf09d (2.14.3): four zone readers, machine checks,
the live installation read-only, probes from outside. No critical; one high
(A2: a stolen global session sets its own password on the user form and so
passes backup-reauth), seven mediums (M1, M2, M3, W1, I1, I2, A1), the rest
low and nits; "checked and sound" per zone; doc drift; a seven-stage plan
with hours and a recommendation. The host's own findings are in dev/, not
published.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
mixandClaude Opus 5.5