These are CVEs in the base image and in standard lib dependencies. For example, just scanned an unhardened image I built today:

  Unhardened: docker.io/nanoco/nanoclaw:agent-alpha
  71 packages, 344 unique CVEs, linux/arm64

  PACKAGE         VERSION        TYP   C   H   M   L   N  TOT
  -----------------------------------------------------------
  expat           2.5.0          deb   0   4  18   1   2   25
  curl            7.88.1         deb   4   4   6   0   7   21
  hono            4.12.14        npm   0   1  18   2   0   21
  libtiff         4.5.0          deb   0   2   1   1  15   20
  perl            5.36.0         deb   5   6   3   0   3   17
  pnpm            10.33.0        npm   0   8   7   0   0   15
  glibc           2.36           deb   1   2   2   1   7   13
  openjpeg        2.5.0          deb   0   0   3   1   9   13
  cups            2.4.2          deb   0   2   8   0   1   11
  glib2           2.74.6         deb   1   7   1   0   1   10
  tar             1.34(+2)       deb   1   1   7   0   1   10
  llvm            15.0.6         deb   0   0   0   1   9   10
  sqlite3         3.40.1         deb   1   2   3   0   3    9
  nss             3.87.1         deb   1   0   3   0   4    8
  avahi           0.8            deb   0   0   8   0   0    8
  util-linux      2.38.1         deb   0   0   3   0   2    7
  elf             0.188          deb   0   0   0   0   7    7
  libssh2         1.10.0         deb   1   4   1   0   0    6
  openldap        2.5.13         deb   0   1   0   0   5    6
  chromium        151.0.7922.108 deb   0   5   0   0   0    5
  -----------------------------------------------------------
  UNIQUE CVEs                         16  68 121  17 119  344

  (+51 more packages, 102 findings)

  C/H/M/L/N = critical/high/medium/low/negligible.
  Counts are unique CVEs: binaries from one source package are
  grouped (libcurl4 + libcurl3-gnutls + curl = curl), so a CVE
  hitting three of them counts once, not three times.