Impact
A brace pattern with a zero step value (e.g., {1..2..0}) causes the sequence generation loop to run indefinitely, making the process hang for seconds and allocate heaps of memory.
The loop in question:
|
for (let i = x; test(i, y); i += incr) { |
test() is one of
|
function lte(i: number, y: number) { |
|
return i <= y |
|
} |
|
|
|
function gte(i: number, y: number) { |
|
return i >= y |
|
} |
The increment is computed as Math.abs(0) = 0, so the loop variable never advances. On a test machine, the process hangs for about 3.5 seconds and allocates roughly 1.9 GB of memory before throwing a RangeError. Setting max to any value has no effect because the limit is only checked at the output combination step, not during sequence generation.
This affects any application that passes untrusted strings to expand(), or by error sets a step value of 0. That includes tools built on minimatch/glob that resolve patterns from CLI arguments or config files. The input needed is just 10 bytes.
Patches
Upgrade to versions
A step increment of 0 is now sanitized to 1, which matches bash behavior.
Workarounds
Sanitize strings passed to expand() to ensure a step value of 0 is not used.
subhashdasyam Finder
katzj Coordinator
Impact
A brace pattern with a zero step value (e.g.,
{1..2..0}) causes the sequence generation loop to run indefinitely, making the process hang for seconds and allocate heaps of memory.The loop in question:
brace-expansion/src/index.ts
Line 184 in daa71bc
test()is one ofbrace-expansion/src/index.ts
Lines 107 to 113 in daa71bc
The increment is computed as
Math.abs(0) = 0, so the loop variable never advances. On a test machine, the process hangs for about 3.5 seconds and allocates roughly 1.9 GB of memory before throwing aRangeError. Setting max to any value has no effect because the limit is only checked at the output combination step, not during sequence generation.This affects any application that passes untrusted strings to expand(), or by error sets a step value of
0. That includes tools built on minimatch/glob that resolve patterns from CLI arguments or config files. The input needed is just 10 bytes.Patches
Upgrade to versions
A step increment of 0 is now sanitized to 1, which matches bash behavior.
Workarounds
Sanitize strings passed to
expand()to ensure a step value of0is not used.