CVE-2026-5477
Detail
Description
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->totalSz != 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.
Metrics
NVD enrichment efforts reference publicly available information to associate
vector strings. CVSS information contributed by other sources is also
displayed.
CVSS 4.0 Severity and Vector Strings:
NVD assessment
not yet provided.
Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N
CVSS 3.x Severity and Vector Strings:
Vector:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
CVSS 2.0 Severity and Vector Strings:
Base
Score:
NVD assessment
not yet provided.
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Weakness Enumeration
| CWE-ID |
CWE Name |
Source |
|
CWE-190
|
Integer Overflow or Wraparound |
wolfSSL Inc.
|
Change History
4 change records found show changes
CVE Modified by CISA-ADP
6/17/2026 6:59:06 AM
| Action |
Type |
Old Value |
New Value |
| Added |
SSVC |
{"timestamp":"2026-04-10T14:03:53.265423Z","id":"CVE-2026-5477","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"role":"CISA Coordinator","version":"2.0.3"}
|
CVE Modified by wolfSSL Inc.
6/17/2026 6:59:06 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Affected |
[{"vendor":"wolfSSL","product":"wolfSSL","defaultStatus":"unaffected","modules":["wc_CmacUpdate"],"programFiles":["wolfcrypt/src/cmac.c","wolfcrypt/src/aes.c"],"versions":[{"version":"0","lessThanOrEqual":"5.9.0","versionType":"semver","status":"affected"}]}]
|
Initial Analysis by NIST
4/27/2026 1:51:47 PM
| Action |
Type |
Old Value |
New Value |
| Added |
CVSS V3.1 |
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
|
| Added |
CPE Configuration |
OR
*cpe:2.3:a:wolfssl:wolfssl:*:*:*:*:*:*:*:* versions up to (including) 5.9.0
|
| Added |
Reference Type |
wolfSSL Inc.: https://github.com/wolfSSL/wolfssl/pull/10102 Types: Issue Tracking
|
New CVE Received from wolfSSL Inc.
4/10/2026 2:16:05 AM
| Action |
Type |
Old Value |
New Value |
| Added |
Description |
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->totalSz != 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.
|
| Added |
CVSS V4.0 |
AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
|
| Added |
CWE |
CWE-190
|
| Added |
Reference |
https://github.com/wolfSSL/wolfssl/pull/10102
|
Quick Info
CVE Dictionary Entry: CVE-2026-5477 NVD
Published Date: 04/10/2026 NVD
Last Modified: 06/17/2026
Source: wolfSSL Inc.
|
