How severe is CVE-2019-8400?

CVE-2019-8400 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2019-8400 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-8400?

CVE-2019-8400 primarily affects Ory Hydra. In total, 129 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-8400?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2019-8400 published?

CVE-2019-8400 was published on 2019-02-17 and last updated on 2026-06-17.

CVE-2019-8400

CVE-2019-8400 is a medium-severity vulnerability in Ory Hydra with a CVSS 3.x base score of 6.1. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 6.1)
CVSS v2: 4.3
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Ory Hydra
Published: 2019-02-17
Last modified: 2026-06-17

Description

ORY Hydra before v1.0.0-rc.3+oryOS.9 has Reflected XSS via the oauth2/fallbacks/error error_hint parameter.

Frequently asked questions

What is CVE-2019-8400?: ORY Hydra before v1.0.0-rc.3+oryOS.9 has Reflected XSS via the oauth2/fallbacks/error error_hint parameter.
How severe is CVE-2019-8400?: CVE-2019-8400 has a CVSS 3.x base score of 6.1, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2019-8400 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-8400?: CVE-2019-8400 primarily affects Ory Hydra. In total, 129 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-8400?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-8400 published?: CVE-2019-8400 was published on 2019-02-17 and last updated on 2026-06-17.

References

Affected products (129)

cpe:2.3:a:ory:hydra:0.1:beta1:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.1:beta2:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.1:beta3:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.1:beta4:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.2.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.3.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.3.1:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.1:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:alpha:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:alpha1:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:alpha2:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:alpha3:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.2:alpha4:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.4.3:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.1:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.2:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.3:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.4:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.5:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.6:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.7:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.5.8:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.1:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.2:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.3:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.4:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.5:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.6:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.7:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.8:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.9:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.6.10:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.7.0:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.7.1:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.7.2:*:*:*:*:*:*:*
cpe:2.3:a:ory:hydra:0.7.3:*:*:*:*:*:*:*

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