CVE-2025-47911 — html
MEDIUMCVE-2025-47911 is a medium-severity (CVSS 5.3) vulnerability in golang.org/x/net/html. A fix is available for golang.org/x/net/html — see the affected versions and patch details below.
golang.org/x/net/html has a Quadratic Parsing Complexity issue
Exploitation Status
No confirmed exploitation observed yet
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.
Exploitation and automatability from CISA’s SSVC triage for CVE-2025-47911.
EPSS Exploitation Probability
EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.
How urgent is this, really
CVE-2025-47911 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.
Where this sits among everything scored
Of 379,145 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.
Real-World Exposure
golang.org/x/net/htmlReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.
Description
The html.Parse function in golang.org/x/net/html has quadratic parsing complexity when processing certain inputs, which can lead to denial of service (DoS) if an attacker provides specially crafted HTML content.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | golang.org/x/net/html | all versions | 0.45.0go get golang.org/x/net/html@v0.45.0 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for golang.org/x/net/html, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update golang.org/x/net/html to 0.45.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2025-47911 is resolved across your whole dependency graph.
Workarounds
Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2025-47911 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2025-47911. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Moderate: The `golang.org/x/net/html` package, used across various Red Hat products, is vulnerable to a denial of service due to quadratic parsing complexity in its `html.Parse` function. An attacker providing specially crafted HTML content could exploit this flaw, leading to resource exhaustion and service…
| Product | Fixed in | Advisory |
|---|---|---|
| Cluster Observability Operator 1.5.0 | cluster-observability-operator/distributed-tracing-console-plugin-pf4-rhel9:1782840519 | RHSA-2026:34342 |
| OpenShift API for Data Protection 1.6 | oadp/oadp-velero-rhel9:1784058822 | RHSA-2026:43692 |
| Red Hat Hardened Images | golang1-26-main-1.26.2-1.hum1 | RHSA-2026:7291 |
| Red Hat Hardened Images | golang1-25-main-1.25.9-1.hum1 | RHSA-2026:7385 |
| Red Hat Openshift Data Foundation 4.22 | odf4/cephcsi-rhel9:1782932114 | RHSA-2026:37387 |
Frequently Asked Questions
Is CVE-2025-47911 in your dependencies?
O3 Security finds CVE-2025-47911 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.