StdOutStream: backport 7-Zip 26.01 terminal escape filter - #260
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Upstream 7-Zip 26.01 (released 2026-04-27) replaced the narrow
"\a \b \t \n \v \f \r" filter in CStdOutStream::Normalize_UString
with a comprehensive IsDangerousTerminalChar() that also covers:
- all of the C0 controls (0x00..0x1F), including ESC (0x1b)
- DEL (0x7F) and the C1 controls (0x80..0x9F), including the 0x9B
8-bit CSI byte that terminals treat as start-of-escape-sequence
- Unicode BiDi override characters 0x202A..0x202E (LRE/RLE/PDF/LRO/RLO)
and 0x2066..0x2069 (LRI/RLI/FSI/PDI), the "Trojan Source" family.
p7zip's pre-existing filter was even narrower than upstream 26.00 --
it covered c >= 7 && c <= 13 but lacked ESC (0x1b). With only those
bytes filtered, an attacker who supplies an archive can embed BiDi
override codepoints in an entry name (which the listing path prints
verbatim) so that the displayed name disagrees with the on-disk name --
e.g. a file shown as "safe.txt" but actually written as "exe.tnp".
Similarly the 0x9B CSI byte was not filtered, allowing an archive name
to inject raw ANSI escape sequences into the user's terminal when
running 7z l / 7z x.
Patch matches upstream 7-Zip 26.01 source.
Signed-off-by: tonghuaroot <tonghuaroot@gmail.com>
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Backports the terminal escape filter expansion landed in upstream 7-Zip 26.01 (released 2026-04-27) to keep parity with mainline on
CStdOutStream::Normalize_UString.What changed upstream
CPP/Common/StdOutStream.cppin p7zip filters only\a \b \t \v \f \r(c >= 7 && c <= 13) when printing strings sourced from archives (entry names, error / warning messages) to the user's terminal. p7zip's filter is even narrower than 7-Zip 26.00 -- it lacks ESC (0x1b).7-Zip 26.01 replaces the narrow check with
IsDangerousTerminalChar()which also filters:0x00..0x1F, including ESC0x7F) and the C1 control range0x80..0x9F, including0x9Bwhich terminals treat as the 8-bit CSI start-of-escape byte0x202A..0x202E(LRE/RLE/PDF/LRO/RLO) and0x2066..0x2069(LRI/RLI/FSI/PDI), the "Trojan Source" familyImpact
Archive entry names are attacker-controlled UTF-16 strings printed verbatim by
7z land during7z x. With onlyc >= 7 && c <= 13filtered, an archive can:0x1b(ESC) or0x9Bfollowed by ANSI sequences to overwrite earlier terminal output.Patch
The hunk matches the upstream 7-Zip 26.01 source.
Normalize_UString_Pathreaches the same code path throughNormalize_UString, so callers that print paths during list/extract get the fix transparently.Disclosure
I am not a native English speaker. AI tooling was used to polish the prose in this PR description. The fix itself is a direct backport from upstream 7-Zip 26.01 source; no design choices were made beyond matching upstream verbatim.