Trying to import the attached file to gpgsm v2.4.3 fails.
gpgsm --debug x509 --import ov-user-ff.p12 ... gpgsm: DBG: p12_parse(tlv_next): ti.class=0 tag=16 len=0 nhdr=2 cons ndef gpgsm: p12_parse(pfxVersion): offset 1.0 (tlv_next): Erfolg - Erfolg ...
The tlv_next before tlv_expect_integer returns 03003FFF (GPG_ERR_EOF, I guess?).
https://dev.gnupg.org/source/gnupg/browse/master/sm/minip12.c;gnupg-2.4.3$2379
Further down, parse_ber_header gets called with length = 0.
https://dev.gnupg.org/source/gnupg/browse/master/common/tlv.c$173
Could it be a problem with ASN.1 sequences of indefinite length that FF uses? Apparently tlv->ndef is set correctly, but a check (between those two lines?) may be missing.
Background:
The attached file is ov-user.p12 from the test suite, which has gone through Firefox (Settings > Security > Certificates... > Import... (pw: start), then Save...).