mbedtls/ChangeLog.d/ssl-mac-zeroize.txt
Gilles Peskine d8e2e8347b Zeroize local MAC variables
Zeroize local MAC variables used for CBC+HMAC cipher suites. In encryption,
this is just good hygiene but probably not needed for security since the
data protected by the MAC that could leak is about to be transmitted anyway.
In DTLS decryption, this could be a security issue since an adversary could
learn the MAC of data that they were trying to inject. At least with
encrypt-then-MAC, the adversary could then easily inject a datagram with
a corrected packet. TLS would still be safe since the receiver would close
the connection after the bad MAC.

Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>
2021-12-11 14:24:23 +01:00

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Security
* Zeroize intermediate variables used to calculate the MAC in CBC cipher
suites. This hardens the library in case stack memory leaks through a
memory disclosure vulnerabilty, which could formerly have allowed a
man-in-the-middle to inject fake ciphertext into a DTLS connection.