CVE-2026-18535IBM API Connect regular expression denial of service
CVE-2026-18535 is a regular expression denial of service in IBM API Connect, rated critical (9.6 on CVSS 3.1).
Why this priority: Critical severity, with no exploitation signal yet.
Published · Updated · NVD status: Undergoing Analysis
What it is
A crafted string makes a regular expression run for a very long time.
How it is reached
An attacker can exploit it over the network, with an ordinary user account, and nobody has to click anything.
What an attacker gains
A successful attack can read the data it protects and take it offline. In practice, this kind of flaw lets an attacker exhaust CPU, memory or connections until the service stops answering. The damage can spread past the vulnerable component into others.
Is it being exploited?
There is no public report of exploitation yet.
What to do
- No fixed version is listed yet. Find every place IBM API Connect runs, watch the references for a fix, and plan a replacement if it is no longer supported.
- While there is no fix, review who holds accounts that can reach it.
Description from NVD
IBM API Connect 10.0.8.0 through 10.0.8.12 and 12.1.0.0 through 12.1.1.2 are vulnerable to a Regular Expression Denial of Service (ReDoS) attack and to improper neutralisation of wildcard query operators.
What this means for your architecture.
A CVE names a product. Whether it matters depends on where that product sits in your systems: what reaches it, which trust boundary it guards and what it can reach once compromised. Veriom maps your components, their relationships and your trust boundaries from your code, cloud and delivery evidence, so you can see where a component like this sits. The radar itself does not look at your systems.
Components it touches
- Public entry points and shared services that must stay up. The flaw sits between untrusted traffic and shared capacity.
Trust boundaries in play
- Authenticated network access. An account is needed, so exposure follows who can sign in: customers, partners or staff.
- Isolation between components. The impact crosses out of the vulnerable component into others it should be isolated from.
- Between untrusted traffic and shared capacity. An attacker who crosses it can exhaust CPU, memory or connections until the service stops answering.
Questions to answer about your own systems
- Where does IBM API Connect run in your systems, and at which version?
- Which of those instances can be reached from the internet or partner networks?
- What can it reach once compromised: which data stores, secrets and services?
Sources
- CVE records and CVSS scores from the NVD CVE API. This product uses the NVD API but is not endorsed or certified by the NVD.
- Exploitation status from CISA’s Known Exploited Vulnerabilities catalog.
- Exploit likelihood from FIRST’s Exploit Prediction Scoring System (EPSS), refreshed daily.
- Explanations are written by Veriom from fixed templates over each record’s data, not by a person reviewing each CVE. Descriptions are quoted from the records as published.