CVE-2026-39388
OpenBao's Certificate Authentication Allows Token Renewal With Different Certificate
Description
### Background OpenBao's Certificate authentication method, when a token renewal is requested and `disable_binding=true` is set, attempts to verify the current request's presented mTLS certificate matches the original. Token renewals for other authentication methods do not require any supplied login information. ### Impact Due to incorrect matching, the certificate authentication method would allow renewal of tokens for which the attacker had a sibling certificate+key signed by the same CA, but which did not necessarily match the original role or the originally supplied certificate. This implies an attacker could still authenticate to OpenBao in a similar scope, however, token renewal implies that an attacker may be able to extend the lifetime of dynamic leases held by the original token. This attack requires knowledge of either the original token or its accessor. This vulnerability is originally from HashiCorp Vault. ### Patches This has been addressed in v2.5.3. ### Workarounds Ensure privileged roles are tightly scoped to single certificates.
How to fix CVE-2026-39388
To remediate CVE-2026-39388, upgrade the affected package to a fixed version below.
- —upgrade to 0.0.0-20260420160924-abe84e1af4c3 or later
Is CVE-2026-39388 being exploited?
Low — EPSS is 0.0%, meaning exploitation activity has not been observed at scale.
Affected packages (1)
- from 0, < 0.0.0-20260420160924-abe84e1af4c3
CVSS scores
| Source | Version | Severity | Vector |
|---|---|---|---|
| osv | CVSS 4.0 | — | CVSS:4.0/AV:N/AC:H/AT:P/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N |
| osv | CVSS 3.1 | LOW3.1 | CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N |