OSV-2026-535 Security exception in org.htmlunit.cyberneko.HTMLTagBalancer.endElement
A security exception in the HTMLTagBalancer component can cause a denial of service when processing malformed HTML input.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is OSV-2026-535?
OSV-2026-535 is a denial of service vulnerability in htmlunit, published on 5 Apr 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
OSS-Fuzz report: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=499447433
Crash type: Security exception
Crash state:
org.htmlunit.cyberneko.HTMLTagBalancer.endElement
java.base/sun.nio.cs.CESU_8.updatePositions
java.base/sun.nio.cs.CESU_8$Encoder.encodeArrayLoop
Which versions are affected by OSV-2026-535?
1 open source package ship an affected version, including htmlunit.
| Package | Affected | Fixed in |
|---|---|---|
htmlunit OSS-Fuzz | All versions | None |
How do I fix OSV-2026-535?
No fix has been published for OSV-2026-535 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is OSV-2026-535 being exploited?
There is no known exploitation of OSV-2026-535 in the wild and no public exploit code.