What is CVE-2021-23840?

CVE-2021-23840 is a high-severity vulnerability in Fujitsu M10-1, classified under Integer Overflow or Wraparound. CVSS score: 7.5/10. Published 2021-02-16.

How severe is CVE-2021-23840?

High severity. CVSS v3 base score is 7.5 out of 10.

Is CVE-2021-23840 known to be exploited?

15 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Integer overflow in Fujitsu M10-1

CVE-2021-23840

Calls to EVP_CipherUpdate, EVP_EncryptUpdate and EVP_DecryptUpdate may overflow the output length argument in some cases where the input length is close to the maximum permissable length for an integer on the platform. In such cases the return value from the function call will be 1 (indicating success), but the output length value will be negative. This could cause applications to behave incorrectly or crash. OpenSSL versions 1.1.1i and below are affected by this issue. Users of these versions should upgrade to OpenSSL 1.1.1j. OpenSSL versions 1.0.2x and below are affected by this issue. However OpenSSL 1.0.2 is out of support and no longer receiving public updates. Premium support customers of OpenSSL 1.0.2 should upgrade to 1.0.2y. Other users should upgrade to 1.1.1j. Fixed in OpenSSL 1.1.1j (Affected 1.1.1-1.1.1i). Fixed in OpenSSL 1.0.2y (Affected 1.0.2-1.0.2x).

Vulnerability class: Integer Overflow

EPSS: 0.507 (98.9th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 7.5 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

Affected products

Weakness classification (CWE)

CWE-190 — Integer Overflow or Wraparound

Public proof-of-concept exploits

References

openssl-security@openssl.org (Vendor Advisory)
openssl-security@openssl.org
openssl-security@openssl.org
openssl-security@openssl.org (vendor-advisory, Third Party Advisory)
openssl-security@openssl.org (vendor-advisory, Third Party Advisory)
openssl-security@openssl.org (Patch, Third Party Advisory)
openssl-security@openssl.org (Third Party Advisory)
openssl-security@openssl.org (Third Party Advisory)
openssl-security@openssl.org (Third Party Advisory)
openssl-security@openssl.org (Third Party Advisory)

Frequently asked questions

What is CVE-2021-23840?: CVE-2021-23840 is a high-severity vulnerability in Fujitsu M10-1, classified under Integer Overflow or Wraparound. CVSS score: 7.5/10. Published 2021-02-16.
How severe is CVE-2021-23840?: High severity. CVSS v3 base score is 7.5 out of 10.
Is CVE-2021-23840 known to be exploited?: 15 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.