How severe is CVE-2019-16782?

CVE-2019-16782 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2019-16782 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2019-16782?

CVE-2019-16782 primarily affects Rack. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2019-16782?

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

When was CVE-2019-16782 published?

CVE-2019-16782 was published on 2019-12-18 and last updated on 2026-06-17.

CVE-2019-16782

CVE-2019-16782 is a medium-severity vulnerability in Rack with a CVSS 3.x base score of 6.3. 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-203.

Key facts

Severity: Medium (CVSS 3.x base score 6.3)
CVSS v2: 4.3
EPSS exploit prediction: 4% (88th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-203
Affected product: Rack
Published: 2019-12-18
Last modified: 2026-06-17

Description

There's a possible information leak / session hijack vulnerability in Rack (RubyGem rack). This vulnerability is patched in versions 1.6.12 and 2.0.8. Attackers may be able to find and hijack sessions by using timing attacks targeting the session id. Session ids are usually stored and indexed in a database that uses some kind of scheme for speeding up lookups of that session id. By carefully measuring the amount of time it takes to look up a session, an attacker may be able to find a valid session id and hijack the session. The session id itself may be generated randomly, but the way the session is indexed by the backing store does not use a secure comparison.

Frequently asked questions

What is CVE-2019-16782?: There's a possible information leak / session hijack vulnerability in Rack (RubyGem rack). This vulnerability is patched in versions 1.6.12 and 2.0.8. Attackers may be able to find and hijack sessions by using timing attacks targeting the session id. Session ids are usually stored and indexed in a database that uses some kind of scheme for speeding up lookups of that session id. By carefully measuring the amount of time it takes to look up a session, an attacker may be able to find a valid session id and hijack the session. The session id itself may be generated randomly, but the way the session is indexed by the backing store does not use a secure comparison.
How severe is CVE-2019-16782?: CVE-2019-16782 has a CVSS 3.x base score of 6.3, rated medium severity. It is exploitable over network with high attack complexity, requires low privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2019-16782 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 4% (88th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2019-16782?: CVE-2019-16782 primarily affects Rack. In total, 3 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2019-16782?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2019-16782 published?: CVE-2019-16782 was published on 2019-12-18 and last updated on 2026-06-17.

References

Affected products (3)

cpe:2.3:a:rack:rack:*:*:*:*:*:ruby:*:*
cpe:2.3:o:fedoraproject:fedora:31:*:*:*:*:*:*:*
cpe:2.3:o:opensuse:leap:15.1:*:*:*:*:*:*:*

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