How severe is CVE-2026-25547?

No CVSS score has been assigned to CVE-2026-25547 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-25547?

CVE-2026-25547 affects the following packages: @isaacs/brace-expansion (npm). Ecosystems affected: npm.

How do I fix CVE-2026-25547?

Update @isaacs/brace-expansion to 5.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25547 is resolved across your whole dependency graph.

How do I detect CVE-2026-25547 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @isaacs/brace-expansion, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2026-25547 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2026-25547?

O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-25547 can be triaged on real exposure rather than presence alone.

Is CVE-2026-25547 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-25547 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2026-25547?

CVE-2026-25547 has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 42th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2026-25547?

CVE-2026-25547 is classified as CWE-1333 (CWE-1333). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2026-25547 published, and has it been updated?

CVE-2026-25547 was published on February 4, 2026 and was last updated on August 12, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-25547: @isaacs/brace DoS

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
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 CVE-2026-25547.

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs42th percentile — riskier than 42% of all scored CVEsHighest risk

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.

Real-World Exposure

1 pkg affected

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.

6other npm packages depend on this — each one inherits the vulnerability until it's patched upstream

@isaacs/brace-expansionnpm

7.7Mdownloads / week

Description

@isaacs/brace-expansion is a hybrid CJS/ESM TypeScript fork of brace-expansion. Prior to version 5.0.1, @isaacs/brace-expansion is vulnerable to a denial of service (DoS) issue caused by unbounded brace range expansion. When an attacker provides a pattern containing repeated numeric brace ranges, the library attempts to eagerly generate every possible combination synchronously. Because the expansion grows exponentially, even a small input can consume excessive CPU and memory and may crash the Node.js process. This issue has been patched in version 5.0.1.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`@isaacs/brace-expansion`	all versions	5.0.1`npm install @isaacs/brace-expansion@5.0.1`

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @isaacs/brace-expansion, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update @isaacs/brace-expansion to 5.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-25547 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 CVE-2026-25547 can be triaged on real exposure rather than presence alone.

Tailored to CVE-2026-25547. 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.

Red HatModerate

Exploitation of this flaw requires that a user or service processes untrusted input.

Product	Fixed in	Advisory
Red Hat Enterprise Linux 10	`nodejs22-1:22.22.2-1.el10_1`	RHSA-2026:7080
Red Hat Enterprise Linux 10	`nodejs24-1:24.14.1-2.el10_1`	RHSA-2026:7675
Red Hat Enterprise Linux 10.0 Extended Update Support	`nodejs22-1:22.22.2-2.el10_0`	RHSA-2026:7310
Red Hat Enterprise Linux 8	`nodejs:22-8100020260331102257.6d880403`	RHSA-2026:7123
Red Hat Enterprise Linux 9	`nodejs:22-9070020260401095228.rhel9`	RHSA-2026:7302
Red Hat Enterprise Linux 9	`nodejs:24-9070020260402152654.rhel9`	RHSA-2026:7350
Red Hat Enterprise Linux 9.6 Extended Update Support	`nodejs:22-9060020260409121057.rhel9`	RHSA-2026:7983

Frequently Asked Questions

@isaacs/brace-expansion is a hybrid CJS/ESM TypeScript fork of brace-expansion. Prior to version 5.0.1, @isaacs/brace-expansion is vulnerable to a denial of service (DoS) issue caused by unbounded brace range expansion. When an attacker provides a pattern containing repeated numeric brace ranges, the library attempts to eagerly generate every possible combination synchronously. Because the expansion grows exponentially, even a small input can consume excessive CPU and memory and may crash the Node.js process. This issue has been patched in version 5.0.1.

O3 Security · Impact-Aware SCA

Is CVE-2026-25547 in your dependencies?

O3 Security finds CVE-2026-25547 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

Scan my dependencies How O3 SCA works

CVE-2026-25547 — @isaacs/brace-expansion