CVE-2026-13149

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:

1. 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.
2. 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.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Simple monitor script for use during development of a node.js app. For use during development of a node.js based application. nodemon will watch the files in the directory in which nodemon was started, and if any files change, nodemon will automatically restart your node application. nodemon does not require any changes to your code or method of development. nodemon simply wraps your node application and keeps an eye on any files that have changed. Remember that nodemon is a replacement wrapper for node, think of it as replacing the word "node" on the command line when you run your script.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a platform built on Chrome's JavaScript runtime \ for easily building fast, scalable network applications. \ Node.js uses an event-driven, non-blocking I/O model that \ makes it lightweight and efficient, perfect for data-intensive \ real-time applications that run across distributed devices.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)

• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

brace-expansion through 5.0.6 is vulnerable to denial of service. The expand() function exhibits exponential-time complexity in the number of consecutive non-expanding '{}' brace groups. An attacker who passes a crafted string to expand(), directly or transitively, can cause significant CPU consumption and event-loop blocking. The max option does not mitigate this, as it bounds the output size rather than the recursion work.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a software development platform for building fast and scalable network applications in the JavaScript programming language.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Simple monitor script for use during development of a node.js app. For use during development of a node.js based application. nodemon will watch the files in the directory in which nodemon was started, and if any files change, nodemon will automatically restart your node application. nodemon does not require any changes to your code or method of development. nodemon simply wraps your node application and keeps an eye on any files that have changed. Remember that nodemon is a replacement wrapper for node, think of it as replacing the word "node" on the command line when you run your script.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a platform built on Chrome's JavaScript runtime \ for easily building fast, scalable network applications. \ Node.js uses an event-driven, non-blocking I/O model that \ makes it lightweight and efficient, perfect for data-intensive \ real-time applications that run across distributed devices.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Node.js is a platform built on Chrome's JavaScript runtime for easily building fast, scalable network applications. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient, perfect for data-intensive real-time applications that run across distributed devices.

Security Fix(es):

• brace-expansion: Brace-expansion: Denial of Service due to exponential-time complexity (CVE-2026-13149)
• tar: Node-tar: Denial of Service via malformed tar archive header (CVE-2026-59874)
• tar: node-tar: Denial of Service via crafted gzip bomb (CVE-2026-59873)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

TuxCare rebuilt brace-expansion to address 1 CVE. Fixed in 2.0.1-tuxcare.2.

TuxCare rebuilt brace-expansion to address 4 CVEs. Fixed in 1.1.11-tuxcare.3.

TuxCare rebuilt brace-expansion to address 6 CVEs. Fixed in 5.0.5-tuxcare.2.

TuxCare rebuilt brace-expansion to address 4 CVEs. Fixed in 5.0.4-tuxcare.3.

TuxCare rebuilt brace-expansion to address 3 CVEs. Fixed in 1.1.14-tuxcare.4.

TuxCare rebuilt brace-expansion to address 4 CVEs. Fixed in 1.1.12-tuxcare.5.

TuxCare rebuilt brace-expansion to address 3 CVEs. Fixed in 1.1.15-tuxcare.4.

TuxCare rebuilt brace-expansion to address 4 CVEs. Fixed in 4.0.1-tuxcare.3.

TuxCare rebuilt brace-expansion to address 4 CVEs. Fixed in 2.0.2-tuxcare.4.

TuxCare rebuilt brace-expansion to address 6 CVEs. Fixed in 5.0.6-tuxcare.1.

TuxCare rebuilt brace-expansion to address 7 CVEs. Fixed in 5.0.3-tuxcare.1.

TuxCare rebuilt brace-expansion to address 7 CVEs. Fixed in 5.0.2-tuxcare.1.

TuxCare rebuilt brace-expansion to address 3 CVEs. Fixed in 1.1.3-tuxcare.3.

These are all security issues fixed in the python313-pytest-html-4.2.0-4.1 package on the GA media of openSUSE Tumbleweed.

These are all security issues fixed in the agama-integration-tests-1785848065.5562c7c-4.1 package on the GA media of openSUSE Tumbleweed.

These are all security issues fixed in the agama-web-ui-24+0.a836cced5-52.1 package on the GA media of openSUSE Tumbleweed.