GHSA-f886-m6hf-6m8v is a medium-severity (CVSS 6.5) Uncontrolled Resource Consumption vulnerability in brace-expansion. A fix is available for brace-expansion — see the affected versions and patch details below.
brace-expansion: Zero-step sequence causes process hang and memory exhaustion
Exploitation Status
No confirmed exploitation observed yet
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for GHSA-f886-m6hf-6m8v.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
GHSA-f886-m6hf-6m8v plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.
brace-expansionnpmDescription
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:
test() is one of
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.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | brace-expansion | ≥ 4.0.0&&< 5.0.5 | 5.0.5npm install brace-expansion@5.0.5 |
| 📦npm | brace-expansion | ≥ 3.0.0&&< 3.0.2 | 3.0.2npm install brace-expansion@3.0.2 |
| 📦npm | brace-expansion | ≥ 2.0.0&&< 2.0.3 | 2.0.3npm install brace-expansion@2.0.3 |
| 📦npm | brace-expansion | all versions | 1.1.13npm install brace-expansion@1.1.13 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for brace-expansion, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update brace-expansion to 5.0.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-f886-m6hf-6m8v is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-f886-m6hf-6m8v can be triaged on real exposure rather than presence alone.
Tailored to GHSA-f886-m6hf-6m8v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
This vulnerability has been rated as Moderate by Red Hat. The vulnerability requires parsing a malformed pattern that, when parsed, leads to infinite looping, excessive memory allocation, and could result in a DoS. The flaw is rated as Moderate because the vulnerable code in the brace-expansion library is not exposed…
| Product | Fixed in | Advisory |
|---|---|---|
| Red Hat Openshift Data Foundation 4.18 | odf4/cephcsi-rhel9:1786705347 | RHSA-2026:56431 |
| Red Hat Openshift Data Foundation 4.22 | odf4/cephcsi-rhel9:1787057250 | RHSA-2026:56928 |
Frequently Asked Questions
Is GHSA-f886-m6hf-6m8v in your dependencies?
O3 Security finds GHSA-f886-m6hf-6m8v across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.