CVE-2021-23840

Integer overflow in CipherUpdate

High · published February 16, 2021

Patch now

High probability of exploitation

CVSS calls it high at 7.5. It sits in the 98.9th percentile for exploit probability.

CVSS v3.1
7.5
EPSS
51%
Percentile
98.9
In the wild
Unconfirmed
What it is

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).

The record
Technical detail
CVSS v3.1
7.5 · HIGH
Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS v4.0
Not supplied
EPSS
0.50732 · 98.9th percentile
Published
2021-02-16T16:55Z
EPSS history
Timeline
  • 16 FEB 16:55Z
    Integer overflow in CipherUpdate
    cvelistv5