CVE-2026-67550 re2: Out-of-bounds heap read in `exec`/`test`/`match` via attacker-influenced `lastIndex` on a non-ASCII subject → uncatchable process crash (DoS)
An attacker can cause a process crash and potential heap information disclosure by manipulating lastIndex on non-ASCII strings in the re2 library.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-67550?
CVE-2026-67550 is a medium-severity denial of service vulnerability in uhop node-re2, published on 30 Jul 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
re2 provides Node.js bindings for Google's RE2 regular expression engine. Prior to 1.25.2, re2 validates lastIndex against the UTF-8 byte length of a subject but uses it as a UTF-16 code-unit offset in exec, test, match, replace, and split, allowing an attacker-influenced lastIndex on a non-ASCII subject to trigger an out-of-bounds heap read and an uncatchable process crash, with limited heap information disclosure in some cases. This issue is fixed in 1.25.2.
Weakness: CWE-125
Which versions are affected by CVE-2026-67550?
2 open source packages ship an affected version, including re2.
| Package | Affected | Fixed in |
|---|---|---|
re2 npm | All versions | 1.25.2 |
re2 npm | All versions | 1.25.2 |
How do I fix CVE-2026-67550?
Upgrade re2 to 1.25.2 or later.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-67550 being exploited?
It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-67550 exists.
Sources
Also known as CLEANSTART-2026-AX56831, DEBIAN-CVE-2026-67550, GHSA-ff84-5f28-78qj, MINI-qmwh-wxc2-cxc3, UBUNTU-CVE-2026-67550.