{"id":"DEBIAN-CVE-2026-5477","details":"An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags. The function wc_CmacUpdate used the guard `if (cmac-\u003etotalSz != 0)` to skip XOR-chaining on the first block (where digest is all-zeros and the XOR is a no-op). However, totalSz is word32 and wraps to zero after 2^28 block flushes (4 GiB), causing the guard to erroneously discard the live CBC-MAC chain state. Any two messages sharing a common suffix beyond the 4 GiB mark then produce identical CMAC tags, enabling a zero-work prefix-substitution forgery. The fix removes the guard, making the XOR unconditional; the no-op property on the first block is preserved because digest is zero-initialized by wc_InitCmac_ex.","modified":"2026-09-14T17:03:19.591011519Z","published":"2026-04-10T06:16:05.243Z","upstream":["CVE-2026-5477"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-5477"}],"affected":[{"package":{"name":"wolfssl","ecosystem":"Debian:12","purl":"pkg:deb/debian/wolfssl?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.5.4-2","5.5.4-2+deb12u1","5.5.4-2+deb12u2","5.5.4-2+deb12u3","5.5.4-2.1","5.6.4-1","5.6.4-2","5.6.6-1","5.6.6-1.1","5.6.6-1.2","5.6.6-1.3","5.6.6-1.3~exp1","5.7.0-0.1","5.7.0-0.2","5.7.0-0.3","5.7.2-0.1","5.7.2-0.2","5.7.2-0.3","5.7.2-0.4","5.8.2-1","5.8.2-1.1","5.8.2-1.2","5.8.4-1","5.9.0-0.1","5.9.0-0.2","5.9.1-0.1","5.9.2-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-5477.json"}},{"package":{"name":"wolfssl","ecosystem":"Debian:13","purl":"pkg:deb/debian/wolfssl?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["5.7.2-0.1","5.7.2-0.1+deb13u1","5.7.2-0.1+deb13u2","5.7.2-0.2","5.7.2-0.3","5.7.2-0.4","5.8.2-1","5.8.2-1.1","5.8.2-1.2","5.8.4-1","5.9.0-0.1","5.9.0-0.2","5.9.1-0.1","5.9.2-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-5477.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"}]}