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Fencer Intel
medium 6.3

CVE-2019-16782 json

Possible Information Leak / Session Hijack Vulnerability in Rack

published 6y ago modified last mo. also GHSA-hrqr-hxpp-chr3 , EUVD-2019-0795

cvss
6.3
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
3.7%
EPSS 3.7% chance of exploitation in 30 days, percentile 89%
public exploits
0
none known

Summary

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.

Patch / fix

  • rubygems rack 1.6.12, 2.0.8
  • rack rack 1.6.12, 2.0.8
  • ruby-rack Debian 14, Debian 13, Debian 12 2.1.1-2

debian advisories DEBIAN-CVE-2019-16782

  • ruby-rack Ubuntu Pro 14.04 LTS 1.5.2-3+deb8u3ubuntu1~esm3
  • ruby-rack Ubuntu Pro 16.04 LTS 1.6.4-3ubuntu0.2+esm1
  • ruby-rack Ubuntu Pro 18.04 LTS 1.6.4-4ubuntu0.2+esm1
  • ruby-rack Ubuntu Pro 20.04 LTS 2.0.7-2ubuntu0.1+esm1

ubuntu advisories UBUNTU-CVE-2019-16782

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • tfm satellite capsule 6.9, satellite 6.9 6.1-4.el7sat
  • kobo satellite capsule 6.9, satellite capsule 6.8, satellite 6.9 +1 more 0.5.1-1.el7sat
  • pulp satellite capsule 6.9, satellite 6.9 2.21.5-2.el7sat
  • gofer satellite capsule 6.9, satellite capsule 6.8, satellite 6.9 +1 more 2.12.5-7.el7sat
  • future satellite capsule 6.9, satellite capsule 6.8, satellite 6.9 +1 more 0.16.0-11.el7sat
  • ostree satellite capsule 6.9, satellite capsule 6.8, satellite 6.9 +1 more 2017.1-2.atomic.el7
  • foreman satellite capsule 6.9, satellite 6.9 2.3.1.20-1.el7sat
  • katello satellite capsule 6.9, satellite 6.9 3.18.1-3.el7sat

red hat advisories RHSA-2021:1313RHSA-2020:4366RHSA-2020:2480

  • rubygem-actionpack-4_2 OpenStack Cloud Crowbar 9, OpenStack Cloud Crowbar 8, OpenStack Cloud 7 4.2.9-7.9.1
  • rubygem-rack OpenStack Cloud Crowbar 9, OpenStack Cloud Crowbar 8, OpenStack Cloud 7 1.6.13-3.8.1
  • rubygem-rack SLE High Availability Extension 15 SP1, SLE High Availability Extension 15 2.0.8-3.3.1

suse advisories SUSE-SU-2021:1162-1SUSE-SU-2020:2678-1SUSE-SU-2020:0359-1

  • rubygem-rack openSUSE Tumbleweed 3.1.18-1.3
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.22-1.1
  • rubygem-rack openSUSE Tumbleweed 3.1.12-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.11-1.1
  • rubygem-actionpack-6.0 openSUSE Tumbleweed 6.0.4.4-1.1
  • rubygem-rack openSUSE Tumbleweed 2.2.3.1-1.1
  • rubygem-rack-2.2 openSUSE Tumbleweed 2.2.4-1.1
  • ruby3.2-rubygem-rack-2.2 openSUSE Tumbleweed 2.2.7-1.1

opensuse advisories openSUSE-SU-2026:10358-1openSUSE-SU-2026:10286-1openSUSE-SU-2025:14875-1openSUSE-SU-2025:14811-1openSUSE-SU-2024:11821-1openSUSE-SU-2024:12119-1

Is CVE-2019-16782 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2019-16782 updated cvss 5.9

rubygem-rack: hijack sessions by using timing attacks targeting the session id

  • Red Hat OpenStack Platform 10 (Newton) Operational Tools rubygem-rack
    affected: workaround, no fix planned “There is no mitigation for this issue, the flaw can only be resolved by applying updates.”
  • Red Hat Satellite 6 tfm-ror52-rubygem-rack
    affected: workaround, no fix available “There is no mitigation for this issue, the flaw can only be resolved by applying updates.”
  • Red Hat Software Collections rh-ror50-rubygem-rack Red Hat Storage 3 rubygem-rack
    affected: workaround, no fix planned “There is no mitigation for this issue, the flaw can only be resolved by applying updates.”
  • Red Hat CloudForms Management Engine 5.11 cfme 5.11.6.0-1.el8cf, libssh2 1.9.0-2.el8cf, ansible-runner 1.4.6-1.el8ar, cfme-gemset 5.11.6.0-1.el8cf, cfme-appliance 5.11.6.0-1.el8cf, python3-ansible-runner 1.4.6-1.el8ar, +3 more
    fixed: vendor fix “There is no mitigation for this issue, the flaw can only be resolved by applying updates.” RHSA-2020:2480
  • Red Hat Satellite 6.8 tfm 6.1-1.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.3-1.el7sat, gofer 2.12.5-7.el7sat, receptor 0.6.3-1.el7ar, future 0.16.0-11.el7sat, +492 more
    fixed: vendor fix “There is no mitigation for this issue, the flaw can only be resolved by applying updates.” RHSA-2020:4366
  • Red Hat Satellite 6.9 tfm 6.1-4.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.5-2.el7sat, gofer 2.12.5-7.el7sat, libsolv 0.7.12-2.el7pc, receptor 0.6.3-1.el7ar, +646 more
    fixed: vendor fix “There is no mitigation for this issue, the flaw can only be resolved by applying updates.” RHSA-2021:1313
  • Red Hat Satellite Capsule 6.8 tfm 6.1-1.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.3-1.el7sat, gofer 2.12.5-7.el7sat, future 0.16.0-11.el7sat, katello 3.16.0-1.el7sat, +246 more
    fixed: vendor fix “There is no mitigation for this issue, the flaw can only be resolved by applying updates.” RHSA-2020:4366
  • Red Hat Satellite Capsule 6.9 tfm 6.1-4.el7sat, kobo 0.5.1-1.el7sat, pulp 2.21.5-2.el7sat, gofer 2.12.5-7.el7sat, libsolv 0.7.12-2.el7pc, future 0.16.0-11.el7sat, +254 more
    fixed: vendor fix “There is no mitigation for this issue, the flaw can only be resolved by applying updates.” RHSA-2021:1313
show 1 more
  • Red Hat OpenStack Platform 13 (Queens) Operational Tools rubygem-rack Red Hat Satellite 6 tfm-ror51-rubygem-rack
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

3.70% chance of exploitation in the next 30 days, higher than 89% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 6.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N
NVD 3.1 5.9 CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N
NVD 2.0 4.3 AV:N/AC:M/Au:N/C:P/I:N/A:N
GitHub 3.1 6.3 CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:N/A:N

Affected packages

ecosystem package affected fixed in
rubygems rack
<1.6.12
>=2.0.0, <2.0.8
1.6.12
2.0.8

Affected products

  • rack rack

Classification

Weakness
  • CWE-208 Observable Timing Discrepancy
  • CWE-203 Observable Discrepancy

References

Sources

Fencer Intel 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.