CVE-2026-78667 Lack of limit on size of parsed Range headers in net/http
Attackers can cause excessive CPU consumption in Go applications by sending Range headers with many small ranges, leading to denial of service.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-78667?
CVE-2026-78667 is a high-severity denial of service vulnerability in Go standard library net/http, published on 8 Oct 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
When parsing a Range header containing a large number of small ranges, FileServer(FS), ServeContent, and ServeFile(FS) can consume an excessive amount of CPU.
Weakness: CWE-770
Which versions are affected by CVE-2026-78667?
2 open source packages ship an affected version, including golang and stdlib.
| Package | Affected | Fixed in |
|---|---|---|
golang Bitnami | All versions | 1.26.9, 1.27.2 |
stdlib Go | All versions | 1.26.9, 1.27.2 |
How do I fix CVE-2026-78667?
Upgrade golang to a fixed version for your release line: 1.26.9 or 1.27.2.
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-2026-78667 being exploited?
There is no known exploitation of CVE-2026-78667 in the wild and no public exploit code.
Sources
Also known as AZL-108219, AZL-108236, AZL-108351, AZL-108474, AZL-108546, BELL-CVE-2026-78667 and 2207 more.