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Vulnerabilities

Vulnerability · CVE-2026-5477

An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags.

Published Apr 10, 2026 · catalog updated Jun 17, 2026 · An integer overflow existed

Check if you run it

No confirmed exploitation is on record for CVE-2026-5477. EPSS is 0.35%. Act only if a listed version of An integer overflow existed is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (An integer overflow existed).
  • No version range is stored. A customer cannot check an installed version against this record.
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.2
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Not established
Affected products
cpe wolfssl/wolfssl

An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags. The function wc_CmacUpdate used the guard 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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

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  • cpe wolfssl/wolfsslversion unspecified

How to fix CVE-2026-5477

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-5477. EPSS is 0.35%. Act only if a listed version of An integer overflow existed is installed.

Which versions are affected?

Affected version ranges are not on this record. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-190: Integer Overflow. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Apr 10, 2026 · NIST NVD

    Detected

    An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags. The function wc_CmacUpdate used the guard 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 tw

  2. Jun 17, 2026 · NIST NVD

    Updated

    An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags. The function wc_CmacUpdate used the guard 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 tw

Sources

  • CVE.orgVulnerability recordCVE-2026-5477

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-5477

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-2026-5477

    An integer overflow existed in the wolfCrypt CMAC implementation, that could be exploited to forge CMAC tags. The function wc_CmacUpdate used the guard to skip XOR-chaining on the first block (where digest is all-zeros and the XOR is a no-op). However, t

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.