Usually most vulnerabilities listed on the Docker Hub are unable to be fixed since there is not an updated package available via the package manager. Let's go down a few of the list of vulnerabilities in latest, 7, 7.7, 7.7.2 and see if they can be fixed:
debian:jessie base image vulnerabilities (first 2 layers):
Layers in buildpack-deps:jessie (next 3 layers):
I would guess that most of the other vulnerabilities in the buildpack-deps layers will have similar descriptions since the Debian images and all dependent images were built just 2 weeks ago. Skipping down to vulnerabilities in the node layers
Layers of node:7.7.2
c-ares that is built within node itself, but it was patched directly in node with https://github.com/nodejs/node/pull/8849, so I'm not sure why it is still detected as vulnerableThank you for the extensive explanation! As far as the node:7.7.2 layer vulnerability, maybe the scanner is looking at the library version which doesn't reflect the patch as mentioned here: https://github.com/nodejs/node/issues/11728
As stated above,
https://security-tracker.debian.org/tracker/CVE-2014-9761, marked as a "Minor issue" by the Debian Security team so not fix available
However, as you can see here, it's marked as _Critical_.

Is this discrepancy due to a different source of severity information?
Yeah, the "Critical" is based purely on the CVSS score of 9.8. Minor is what the Debian Security team have classified it for their security release process in order to allocate resources effectively in porting security fixes across all packages.
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Usually most vulnerabilities listed on the Docker Hub are unable to be fixed since there is not an updated package available via the package manager. Let's go down a few of the list of vulnerabilities in
latest, 7, 7.7, 7.7.2and see if they can be fixed:debian:jessiebase image vulnerabilities (first 2 layers):Layers in
buildpack-deps:jessie(next 3 layers):I would guess that most of the other vulnerabilities in the
buildpack-depslayers will have similar descriptions since the Debian images and all dependent images were built just 2 weeks ago. Skipping down to vulnerabilities in the node layersLayers of node:7.7.2
c-aresthat is built within node itself, but it was patched directly in node with https://github.com/nodejs/node/pull/8849, so I'm not sure why it is still detected as vulnerable