# CVE-2026-18535: IBM API Connect regular expression denial of service

Source: https://junglewise.ai/threats/cve-2026-18535-ibm-api-connect-10-0-8-0-through-10-0-8-12-and-12-1-0-0-through  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-07. Updated: 2026-11-07  
License: CC BY 4.0 with a link back

CVE-2026-18535 · Severity: critical · CVSS 9.6 · Published 2026-11-07

IBM API Connect is a platform for managing and deploying application programming interfaces (APIs). Versions 10.0.8.0–10.0.8.12 and 12.1.0.0–12.1.1.2 are vulnerable to regular expression denial of service (ReDoS) attacks that can cause the service to become unresponsive or crash, disrupting API traffic and availability.

Technologies: [IBM API Connect](https://junglewise.ai/threats/technologies/api-connect). Vendors: [IBM](https://junglewise.ai/threats/vendors/ibm).

## Quick answers

**Is CVE-2026-18535 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-18535 being exploited in the wild.

**How severe is CVE-2026-18535?** Critical severity, with a CVSS score of 9.6, published 7 November 2026.

**Which products and versions are affected?** IBM API Connect 10.0.8.0 through 10.0.8.12, 12.1.0.0 through 12.1.1.2.

**Is there a fix for CVE-2026-18535?** Yes: fixed in IBM API Connect 10.0.8.13, 12.1.1.3. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-18535 attacked?** It is attacked over the network.

**Am I affected by CVE-2026-18535?** Check whether you run IBM API Connect at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in IBM API Connect 10.0.8.13, 12.1.1.3

## Technical details

The vulnerability is a regular expression denial of service (ReDoS) affecting IBM API Connect in the specified version ranges. An attacker can craft malicious input that causes a regular expression evaluation to consume excessive CPU resources, resulting in denial of service. The attack vector is network-based with no authentication required.

## Affected products

- IBM API Connect 10.0.8.0 through 10.0.8.12, 12.1.0.0 through 12.1.1.2

## Timeline

- 2026-11-07: disclosed

## References

- [https://www.ibm.com/support/pages/node/7291753](https://www.ibm.com/support/pages/node/7291753)
- [https://www.ibm.com/support/pages/node/7292434](https://www.ibm.com/support/pages/node/7292434)

## Related threats

- [IBM API Connect server-side request forgery](https://junglewise.ai/threats/cve-2026-75590-ibm-api-connect-12-1-0-0-through-12-1-1-2-could-allow-a-remote)
- [IBM API Connect missing authorization in index access](https://junglewise.ai/threats/cve-2026-19131-ibm-api-connect-12-1-0-0-through-12-1-1-2-could-allow-low)
- [IBM API Connect improper backup server certificate verification](https://junglewise.ai/threats/cve-2026-19129-ibm-api-connect-10-0-8-0-through-10-0-8-12-and-12-1-0-0-through)
- [IBM API Connect server-side request forgery via unauthorized request](https://junglewise.ai/threats/cve-2026-19128-ibm-api-connect-12-1-0-0-through-12-1-1-2-could-allow-an)
- [IBM API Connect weak cryptographic algorithms in authentication](https://junglewise.ai/threats/cve-2026-19126-ibm-api-connect-10-0-8-0-through-10-0-8-12-and-12-1-0-0-through)