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Ubuntu: USN-4376-2 (CVE-2019-1559): OpenSSL vulnerabilities

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Ubuntu: USN-4376-2 (CVE-2019-1559): OpenSSL vulnerabilities

Severity
4
CVSS
(AV:N/AC:M/Au:N/C:P/I:N/A:N)
Published
02/19/2019
Created
03/19/2019
Added
03/12/2019
Modified
03/22/2023

Description

If an application encounters a fatal protocol error and then calls SSL_shutdown() twice (once to send a close_notify, and once to receive one) then OpenSSL can respond differently to the calling application if a 0 byte record is received with invalid padding compared to if a 0 byte record is received with an invalid MAC. If the application then behaves differently based on that in a way that is detectable to the remote peer, then this amounts to a padding oracle that could be used to decrypt data. In order for this to be exploitable "non-stitched" ciphersuites must be in use. Stitched ciphersuites are optimised implementations of certain commonly used ciphersuites. Also the application must call SSL_shutdown() twice even if a protocol error has occurred (applications should not do this but some do anyway). Fixed in OpenSSL 1.0.2r (Affected 1.0.2-1.0.2q).

Solution(s)

  • ubuntu-upgrade-libssl1-0-0

References

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