`NSC_DeriveKey` inadvertently assumed that the `phKey` parameter is always non-NULL. When it was passed as NULL, a segmentation fault (SEGV) occurred, leading to crashes. This behavior conflicted with the PKCS#11 v3.0 specification, which allows `phKey` to be NULL for certain mechanisms. This vulnerability affects Firefox < 133 and Thunderbird < 133.
https://www.mozilla.org/security/advisories/mfsa2024-67/