The test suite in libopendkim in OpenDKIM through 2.10.3 allows local users to gain privileges via a symlink attack against the /tmp/testkeys file (related to t-testdata.h, t-setup.c, and t-cleanup.c). NOTE: this is applicable to persons who choose to engage in the "A number of self-test programs are included here for unit-testing the library" situation.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-35766
• trusteddomainproject/OpenDKIM#113