GHSA-hrqr-hxpp-chr3: rack (CVE-2019-16782)

Package	Ecosystem	Affected	Fixed in
rack	RubyGems	<1.6.12 \|\| >=2.0.0, <2.0.8	1.6.12, 2.0.8

Machine-written summary

Summary written by Claude Haiku from the source advisory. Not reviewed by a person.

Rack versions below 1.6.12, and versions from 2.0.0 up to but not including 2.0.8, are vulnerable to a timing attack on session ids. An attacker who can send many requests and precisely measure response times could determine a valid session id and hijack that session. Upgrade to Rack 1.6.12 or 2.0.8. The source lists no workarounds.

Written 8 Nov 2026.

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

Score	Rating	CVSS	Vector	Source
6.3	Medium	3.1	CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N	CNA (GitHub_M)

CISA KEV Not listed.
EPSS 0.037, the 89th percentile, on 8 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

18 Dec 2019, 18:16 UTC Published by the maintainers as a GitHub repository advisory
31 Oct 2026, 15:16 UTC First seen by agentprime
31 Oct 2026, 15:16 UTC Confirmed by OSV

Sources

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.