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Fix command injection via Symbol arguments in net-imap.

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Fixes CVE-2026-42258.

Additionally, backport validation regex ATOM_SPECIALS that's needed.

Backported from
1eb27278a6
bbd9eb7ecc
92db350b24

Resolves: RHEL-181808
This commit is contained in:
Jarek Prokop 2026-06-11 18:22:19 +02:00
parent 1087f0b172
commit f0332efed4
2 changed files with 250 additions and 0 deletions
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9
ruby.spec
View File

@ -354,6 +354,12 @@ Patch81: rubygem-erb-4.0.3.1-Fix-arbitrary-code-execution-via-deserialization-by
# https://github.com/ruby/net-imap/commit/d16e994
# https://github.com/ruby/net-imap/commit/6b2fda5
Patch82: rubygem-net-imap-0.3.10-Fix-Information-disclosure-via-man-in-the-middle-attack-bypassing-TLS-CVE-2026-42246.patch
# Fix CVE-2026-42258 IMAP Command Injection via Symbol Arguments.
# https://github.com/ruby/net-imap/commit/1eb27278a601be1135910dae6ab6e517559a2e4a
# https://github.com/ruby/net-imap/commit/bbd9eb7ecca506fa43b656368f7aebef8ac09182
# Additionally, backport validation regex ATOM_SPECIALS that's needed, from
# https://github.com/ruby/net-imap/commit/92db350b24c388d2a2104f36cac9caa49a1044df
Patch83: rubygem-net-imap-0.4.24-Fix-IMAP-Command-Injection-via-Symbol-Arguments-CVE-2026-42258.patch
Requires: %{name}-libs%{?_isa} = %{version}-%{release}
Suggests: rubypick
@ -838,6 +844,7 @@ rm -rf ext/fiddle/libffi*
%patch80 -p1
%patch81 -p1
%patch82 -p1
%patch83 -p1
# Instead of adjusting patch's directory, use the following form where
# we first enter the correct directory, this allows more general application
@ -1624,6 +1631,8 @@ make runruby TESTRUN_SCRIPT=" \
- Fix information disclosure via MITM attack bypassing TLS in net-imap.
(CVE-2026-42246)
Resolves: RHEL-181777
- Fix command injection via Symbol arguments in net-imap. (CVE-2026-42258)
Resolves: RHEL-181808
* Mon Apr 27 2026 Jarek Prokop <jprokop@redhat.com> - 3.0.7-166
- Fix arbitrary code execution via deserialization bypass in ERB. (CVE-2026-41316)

241
rubygem-net-imap-0.4.24-Fix-IMAP-Command-Injection-via-Symbol-Arguments-CVE-2026-42258.patch Normal file
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@ -0,0 +1,241 @@
From ec11376b38dbfbd1dde52d3410def338c7656170 Mon Sep 17 00:00:00 2001
From: nick evans <nick@rubinick.dev>
Date: Wed, 22 Apr 2026 11:25:06 -0400
Subject: [PATCH 1/3] =?UTF-8?q?=F0=9F=8D=92=20edit=20ca72ac45:=20=E2=99=BB?=
=?UTF-8?q?=EF=B8=8F=20Extract=20superclass=20for=20(internal)=20command?=
=?UTF-8?q?=20data?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Unlike the cherry-picked commit (ca72ac45), this _only_ makes
`CommandData` the superclass for `Literal` and `Atom`. Because those
are the classes that will be modified by later cherry-picked commits.
This allows those other commits to merge more cleanly, and work with
fewer modifications.
---
lib/net/imap.rb | 50 +++++++++++++++++++++++++------------------------
1 file changed, 26 insertions(+), 24 deletions(-)
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 1a2afc0ea7..92ff9a0fbe 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -1571,33 +1571,44 @@ def start_tls_session(params = {})
end
end
- class RawData # :nodoc:
- def send_data(imap, tag)
- imap.__send__(:put_string, @data)
+ # simplistic emulation of CommandData = Data.define(:data)
+ class CommandData # :nodoc:
+ class << self
+ def new(arg = nil, data: arg) super(data: data) end
+ alias :[] :new
end
- def validate
+ def initialize(data:)
+ @data = data
+ freeze
end
- private
+ attr_reader :data
- def initialize(data)
- @data = data
- end
- end
+ def to_h(&block) block ? to_h.to_h(&block) : { data: data } end
+ def ==(other) self.class === other && to_h == other.to_h end
+ def eql?(other) self.class === other && to_h.eql?(other.to_h) end
+
+ # following class definition goes beyond the basic Data.define(:data)
+ ##
- class Atom # :nodoc:
def send_data(imap, tag)
- imap.__send__(:put_string, @data)
+ raise NoMethodError, "#{self.class} must implement #{__method__}"
end
def validate
end
+ end
- private
+ class RawData < CommandData # :nodoc:
+ def send_data(imap, tag)
+ imap.__send__(:put_string, @data)
+ end
+ end
- def initialize(data)
- @data = data
+ class Atom < CommandData # :nodoc:
+ def send_data(imap, tag)
+ imap.__send__(:put_string, @data)
end
end
@@ -1616,19 +1627,10 @@ def initialize(data)
end
end
- class Literal # :nodoc:
+ class Literal < CommandData # :nodoc:
def send_data(imap, tag)
imap.__send__(:send_literal, @data, tag)
end
-
- def validate
- end
-
- private
-
- def initialize(data)
- @data = data
- end
end
class MessageSet # :nodoc:
From f793ce76e5f417c011a437418feb8378039e4a37 Mon Sep 17 00:00:00 2001
From: nick evans <nick@rubinick.dev>
Date: Thu, 19 Feb 2026 15:06:08 -0500
Subject: [PATCH 2/3] =?UTF-8?q?=F0=9F=8D=92=20pick=209db3e9d60:=20?=
=?UTF-8?q?=F0=9F=A5=85=20Strictly=20validate=20symbol=20(\flag)=20argumen?=
=?UTF-8?q?ts=20[backports=20#657]?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Flags should not allow `atom-specials`.
Previously, no validation was done on symbol data. Sending atom or flag
args which contain atom specials could lead to various errors.
Although this could theoretically include injection attacks, this is not
considered to be a critical vulnerability in `net-imap`, for the
following reason: Valid "system flag" inputs are restricted to an
enumerated set of RFC-defined flag types. User-defined "keyword" flags
are sent as atoms, not flags, which use string inputs (strings which
can't be sent as an atom will be quoted or sent as a literal). `\Seen`
as a flag (symbol argument) is semantically different from `Seen` as a
keyword (string argument). So there is no scenario where it is
appropriate to call `#to_sym` on unvetted user input. Any code which
calls `#to_sym` indiscriminately on user-input is already buggy.
Nevertheless, users should reasonably be able to rely on `net-imap` to
do very basic input validation on its basic input types.
---
lib/net/imap.rb | 33 +++++++++++++++++++++++++++------
1 file changed, 27 insertions(+), 6 deletions(-)
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 92ff9a0fbe..5dc0638e2f 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -1349,6 +1349,7 @@ def validate_data(data)
end
when Time
when Symbol
+ Flag.validate(data)
else
data.validate
end
@@ -1367,7 +1368,7 @@ def send_data(data, tag = nil)
when Time
send_time_data(data)
when Symbol
- send_symbol_data(data)
+ Flag[data].send_data(self, tag)
else
data.send_data(self, tag)
end
@@ -1437,10 +1438,6 @@ def send_time_data(time)
put_string(s)
end
- def send_symbol_data(symbol)
- put_string("\\" + symbol.to_s)
- end
-
def search_internal(cmd, keys, charset)
if keys.instance_of?(String)
keys = [RawData.new(keys)]
@@ -1592,6 +1589,12 @@ def eql?(other) self.class === other && to_h.eql?(other.to_h) end
# following class definition goes beyond the basic Data.define(:data)
##
+ def self.validate(...)
+ data = new(...)
+ data.validate
+ data
+ end
+
def send_data(imap, tag)
raise NoMethodError, "#{self.class} must implement #{__method__}"
end
@@ -1607,8 +1610,26 @@ def send_data(imap, tag)
end
class Atom < CommandData # :nodoc:
+ def initialize(**)
+ super
+ validate
+ end
+
+ def validate
+ data.to_s.ascii_only? \
+ or raise DataFormatError, "#{self.class} must be ASCII only"
+ data.match?(ResponseParser::Patterns::ATOM_SPECIALS) \
+ and raise DataFormatError, "#{self.class} must not contain atom-specials"
+ end
+
def send_data(imap, tag)
- imap.__send__(:put_string, @data)
+ imap.__send__(:put_string, data.to_s)
+ end
+ end
+
+ class Flag < Atom # :nodoc:
+ def send_data(imap, tag)
+ imap.__send__(:put_string, "\\#{data}")
end
end
From e407aa69f28b71f20eb83145be14ff8a2e57436f Mon Sep 17 00:00:00 2001
From: Jarek Prokop <jprokop@redhat.com>
Date: Tue, 9 Jun 2026 18:14:51 +0200
Subject: [PATCH 3/3] Cherry-pick ATOM_SPECIALS for validation regex.
The previous commit relies on ResponseParsers::Patterns::ATOM_SPECIALS
to be available. We could either hardcode the regex in the line where
the matching happens, but instead have it live in its own constant for
easier reference and less edits to the actual commit backport.
The line ported from:
https://github.com/ruby/net-imap/commit/92db350b24c388d2a2104f36cac9caa49a1044df
---
lib/net/imap.rb | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/lib/net/imap.rb b/lib/net/imap.rb
index 5dc0638e2f..07af17c008 100644
--- a/lib/net/imap.rb
+++ b/lib/net/imap.rb
@@ -2222,6 +2222,10 @@ def multipart?
end
class ResponseParser # :nodoc:
+ module Patterns
+ ATOM_SPECIALS = /[(){ \x00-\x1f\x7f%*"\\\]]/n
+ end
+
def initialize
@str = nil
@pos = nil