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Fencer Vulns
medium 5.8

CVE-2020-5300 json

Disallow replay of `private_key_jwt` by blacklisting JTIs in Hydra

published 2020-04-06 6 y ago modified 2026-07-08 4 mo ago also GHSA-3p3g-vpw6-4w66 , GO-2022-0786 , EUVD-2021-0921

cvss
5.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
1.0%
EPSS 1.0% chance of exploitation in 30 days, percentile 63%
public exploits
0
none known

Summary

In Hydra (an OAuth2 Server and OpenID Certified™ OpenID Connect Provider written in Go), before version 1.4.0+oryOS.17, when using client authentication method 'private_key_jwt' [1], OpenId specification says the following about assertion `jti`: "A unique identifier for the token, which can be used to prevent reuse of the token. These tokens MUST only be used once, unless conditions for reuse were negotiated between the parties". Hydra does not check the uniqueness of this `jti` value. Exploiting this vulnerability is somewhat difficult because: - TLS protects against MITM which makes it difficult to intercept valid tokens for replay attacks - The expiry time of the JWT gives only a short window of opportunity where it could be replayed This has been patched in version v1.4.0+oryOS.17

Patch / fix

  • go github.com/ory/hydra 1.4.0
  • ory hydra 1.4.0

Exploit prediction

1.03% chance of exploitation in the next 30 days, higher than 63% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by version score vector
CNA 3.1 5.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N
NVD 3.1 5.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 3.5 AV:N/AC:M/Au:S/C:P/I:N/A:N
GitHub 3.1 5.8 CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
go github.com/ory/hydra
<1.4.0
1.4.0

Affected products

  • ory hydra

Classification

Weakness
  • CWE-294 Authentication Bypass by Capture-replay

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.