Update dependency brace-expansion to v5 [SECURITY] by renovate[bot] · Pull Request #188 · PrivAtlas/javascript-dlc

renovate · 2026-03-27T14:03:03Z

This PR contains the following updates:

Package	Change	Age	Confidence
brace-expansion	`^4.0.1` → `^5.0.0`

brace-expansion: Zero-step sequence causes process hang and memory exhaustion

CVE-2026-33750 / GHSA-f886-m6hf-6m8v

More information

Details

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:

https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L184

test() is one of

https://github.com/juliangruber/brace-expansion/blob/daa71bcb4a30a2df9bcb7f7b8daaf2ab30e5794a/src/index.ts#L107-L113

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

5.0.5+

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.

Severity

CVSS Score: 6.5 / 10 (Medium)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

brace-expansion: DoS via exponential-time expansion of consecutive non-expanding {} groups

CVE-2026-13149 / GHSA-3jxr-9vmj-r5cp

More information

Details

Summary

brace-expansion's expand() exhibits exponential-time - O(2ⁿ) - behavior in the number of consecutive non-expanding {} groups. A short, all-ASCII input (~90 bytes/30 groups) blocks the calling thread for minutes; a slightly longer input hangs it effectively indefinitely. Because the dominant consumers run on Node's single-threaded event loop, one small input can fully stall a worker/process.

In expand_, post is computed unconditionally at the top of the function, before the early-return branches that don't use it:

const post = m.post.length ? expand_(m.post, max, false) : [''];   // always recurses
  ...
if (!isSequence && !isOptions) {
  if (m.post.match(/,(?!,).*\}/)) {
    str = m.pre + '{' + m.body + escClose + m.post;
    return expand_(str, max, true); // restart — `post` discarded
  }
  return [str];
}

For input like a{},{},…, the first {} is non-expanding, so control reaches the {a},b} rewrite branch - but expand_ has already recursed into post over the entire remaining tail, only to throw the result away.
Each level therefore spawns two recursive expansions over essentially the same remaining work: T(n) = 2·T(n−1) ⇒ O(2ⁿ).

The max option does not mitigate this: max only bounds the output-building loops; neither the post recursion nor the rewrite recursion consults it.

Measured on 5.0.6:

groups (n)	input bytes	time
20	60	130 ms
24	72	1.9 s
26	78	7.8 s
30 (PoC)	90	~2 min

Proof of concept

const { expand } = require('brace-expansion');
// 30 non-expanding groups, ~90 bytes — blocks for minutes:
expand('a{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{},{}');

Impact

Any application that passes attacker-influenced strings to brace-expansion.expand() - directly or transitively via minimatch/glob brace patterns - can be driven into a multi-minute-to-indefinite CPU hang by a tiny request, denying service on that thread/process.

Remediation

Upgrade to a patched release. The fix:

Defers computing post until after the early-return branches (and computes it locally in the $-suffix branch), so post is only expanded when a brace set actually expands and the value is used. This alone removes the exponential.
Converts the {a},b} rewrite from recursion to an in-function loop, so a long run of rewrites cannot grow the call stack.

Verified: the PoC drops from ~2 min to 0.55 ms, 5,000 groups complete in ~344 ms, and output is identical to 5.0.6 across a behavioral-equivalence suite (sequences, padding, $-prefix, a{},b}c, {},a}b, x{{a,b}}y, etc.). Post-fix complexity is ~O(n²) on this input class - acceptable for the security fix; a linear rewrite can be a non-urgent follow-up.

If immediate upgrade isn't possible, avoid passing untrusted input to expand() / glob brace patterns, or run such expansion under a timeout/worker.

Severity

CVSS Score: 7.7 / 10 (High)
Vector String: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:P/S:N/AU:Y/R:U/V:D/RE:M/U:Amber

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

brace-expansion: DoS via unbounded expansion length causing an out-of-memory process crash

CVE-2026-14257 / GHSA-mh99-v99m-4gvg

More information

Details

Summary

expand() bounds the number of results it produces (the max option,
100_000 by default) but not their length. By chaining many brace groups,
an attacker keeps the result count under max while making every result grow
with the number of groups. Building max long results — plus the intermediate
arrays combined at each brace group — exhausts memory and crashes the Node
process with an uncatchable out-of-memory error. try/catch around
expand() does not help: the fatal error terminates the process.

A ~7.5 KB input ('{a,b}'.repeat(1500)) is enough to crash a default Node
process.

Details

For N chained brace groups such as '{a,b}'.repeat(N):

the result count is 2^N, immediately capped at max (100_000), so the
max protection appears to hold, but
each result is N characters long, so the total output size is
max × N characters, which grows without bound in N.

expand_ combines each brace set with the fully-expanded tail:

const post = m.post.length ? expand_(m.post, max, false) : ['']
...
for (let j = 0; j < N.length; j++) {
  for (let k = 0; k < post.length && expansions.length < max; k++) {
    const expansion = pre + N[j] + post[k]   // grows one group longer per level
    ...
    expansions.push(expansion)
  }
}

The loop guard expansions.length < max limits how many strings are built, but
nothing limits how long they get. Each recursion level materializes another
array of up to max strings, one character longer than the level below, and —
because V8 represents pre + N[j] + post[k] as a cons-string (rope) that
references post[k] — those intermediate strings stay reachable through the
whole chain. Memory therefore scales with max × N.

Measured on 5.0.7 ('{a,b}'.repeat(N), default max):

groups (N)	input bytes	result count	peak RSS
20	100	100,000	~80 MB
50	250	100,000	~214 MB
100	500	100,000	~409 MB
300	1,500	100,000	~1,148 MB
1500	7,500	—	OOM crash

Proof of concept

const { expand } = require('brace-expansion')

// ~7.5 KB input — crashes the process with a fatal, uncatchable OOM:
//   FATAL ERROR: ... JavaScript heap out of memory
try {
  expand('{a,b}'.repeat(1500))
} catch (e) {
  // never reached — the process is already dead
}

Impact

Any application that passes attacker-influenced strings to
brace-expansion.expand() — directly, or transitively via minimatch / glob
brace patterns — can be crashed by a small request. Because the failure is a
fatal V8 out-of-memory error rather than a thrown exception, it cannot be caught
and it takes down the whole worker/process, denying service.

Remediation

Upgrade to a patched release. The fix bounds the total number of characters a
single expand() call may accumulate (EXPANSION_MAX_LENGTH, default
4_000_000, configurable via a new maxLength option), applied inside the
output-building loops so intermediate arrays are bounded too. Once the limit is
reached, output is truncated — consistent with how max already truncates —
instead of growing without bound. The limit sits well above any realistic
expansion (100,000 results hitting max measure ~1M characters), so legitimate
input is unaffected.

After the fix, '{a,b}'.repeat(1500) returns a bounded, truncated result in
~0.7 s using ~340 MB and never crashes, including under a constrained 512 MB
heap.

The fix bounds memory but the algorithm still rebuilds intermediate arrays at
each level (roughly O(N × maxLength) work on this input class). A streaming
rewrite that produces output in O(total output size) can be a non-urgent
follow-up.

If immediate upgrade isn't possible, avoid passing untrusted input to
expand() / glob brace patterns, or pass a small explicit max and
maxLength.

Severity

CVSS Score: 7.5 / 10 (High)
Vector String: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

References

This data is provided by the GitHub Advisory Database (CC-BY 4.0).

Release Notes

juliangruber/brace-expansion (brace-expansion)

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This PR was generated by Mend Renovate. View the repository job log.

renovate Bot force-pushed the renovate/npm-brace-expansion-vulnerability branch from e80d744 to cfb3dfe Compare May 12, 2026 16:54

renovate Bot force-pushed the renovate/npm-brace-expansion-vulnerability branch from cfb3dfe to 9196f82 Compare July 12, 2026 11:15

renovate Bot force-pushed the renovate/npm-brace-expansion-vulnerability branch from 9196f82 to 502f7fc Compare July 24, 2026 18:37

Update dependency brace-expansion to v5 [SECURITY]

ce99249

renovate Bot force-pushed the renovate/npm-brace-expansion-vulnerability branch from 502f7fc to ce99249 Compare July 30, 2026 16:35

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Update dependency brace-expansion to v5 [SECURITY] - #188

Update dependency brace-expansion to v5 [SECURITY]#188
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renovate/npm-brace-expansion-vulnerability

renovate Bot commented Mar 27, 2026 •

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brace-expansion: Zero-step sequence causes process hang and memory exhaustion

Details

Impact

Patches

Workarounds

Severity

References

brace-expansion: DoS via exponential-time expansion of consecutive non-expanding {} groups

Details

Summary

Proof of concept

Impact

Remediation

Severity

References

brace-expansion: DoS via unbounded expansion length causing an out-of-memory process crash

Details

Summary

Details

Proof of concept

Impact

Remediation

Severity

References

Release Notes

v5.0.8

v5.0.7

v5.0.6

v5.0.5

v5.0.4

v5.0.3

v5.0.2

Configuration

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renovate Bot commented Mar 27, 2026 •

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`v5.0.8`

`v5.0.7`

`v5.0.6`

`v5.0.5`

`v5.0.4`

`v5.0.3`

`v5.0.2`