CVE-2026-23989 is a high-severity (CVSS 8.2) CWE-863 vulnerability in github.com/opencloud-eu/reva/v2. A fix is available for github.com/opencloud-eu/reva/v2 — see the affected versions and patch details below.
REVA Public Link Exploit
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-2026-23989.
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-2026-23989 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 378,567 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/opencloud-eu/reva/v2🐹github.com/opencloud-eu/reva/v2Real-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
Impact
A security issue was discovered in Reva based products that enables a malicious user to bypass the scope validation of a public link, allowing it to access resources outside the scope of a public link.
Details
Public link shares in OpenCloud are bound to a specific scope (usually a file or directory). Anonymous users accessing resources via this public link share are only allowed to access the share resource itself and, in case of a directory or space root, all child resources of it.
Due to a bug in the GRPC authorization middleware of the "Reva" component of OpenCloud a malicious user is able to bypass the scope verification. By exploiting this via the the "archiver" service this can be leveraged to create an archive (zip or tar-file) containing all resources that this creator of the public link has access to.
It is not possible to bypass the public link scope via "normal" WebDAV requests so it is not possible to exploit this vulnerability via WebDAV.
Patches
Update to OpenCloud Reva version >= 2.40.3 for the 2.40.x versions.
Update to OpenCloud Reva version >= 2.42.3 for the 2.41.x versions
Workarounds
There is no workaround because one cannot run Reva standalone from this project. Please check the OpenCloud Advisory how to mitigate the problem in an OpenCloud deployment via configuration.
For more information
If there are any questions or comments about this advisory:
- Security Support: [email protected]
- Technical Support: [email protected]
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/opencloud-eu/reva/v2 | all versions | 2.40.3go get github.com/opencloud-eu/reva/v2@v2.40.3 |
| 🐹Go | github.com/opencloud-eu/reva/v2 | ≥ 2.41.0&&< 2.42.3 | 2.42.3go get github.com/opencloud-eu/reva/v2@v2.42.3 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/opencloud-eu/reva/v2, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update github.com/opencloud-eu/reva/v2 to 2.40.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23989 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-2026-23989 can be triaged on real exposure rather than presence alone.
Tailored to CVE-2026-23989. 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-2026-23989 in your dependencies?
O3 Security finds CVE-2026-23989 across Go dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.