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+fetchmail-6.3.22 (not yet released):
+
+# SECURITY FIX
+* CVE-2011-3389:
+ SSL/TLS (wrapped and STARTTLS): fetchmail used to disable a countermeasure
+ against a certain kind of attack against cipher block chaining initialization
+ vectors (SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS).
+ Whether this creates an exploitable situation, depends on the server and the
+ negotiated ciphers.
+ As a precaution, fetchmail 6.3.22 enables the countermeasure, by clearing
+ SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS.
+
+ NOTE that this can cause connections to certain non-conforming servers to
+ fail, in which case you can set the environment variable
+ FETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE to any non-empty value when starting
+ fetchmail to re-instate the compatibility option at the expense of security.
+
+ Reported by Apple Product Security.
+
+ For technical details, refer to <http://www.openssl.org/~bodo/tls-cbc.txt>.
+ See fetchmail-SA-2012-01.txt for further details.
+
# BUG FIX
* The Server certificate: message in verbose mode now appears on stdout like the
remainder of the output. Reported by Henry Jensen, to fix Debian Bug #639807.
# CHANGE
* On systems where SSLv2_client_method isn't defined in OpenSSL (such as
newer Debian, and Ubuntu starting with 11.10 oneiric ocelot), don't
- reference it (to fix the build) and print a run-time error that the OS
- does not support SSLv2. Fixes Debian Bug #622054, but note that that bug
- report has a more thorough patch that does away with SSLv2 altogether.
+ reference it (to fix the build) and if configured, print a run-time error
+ that the OS does not support SSLv2. Fixes Debian Bug #622054,
+ but note that that bug report has a more thorough patch that does away with
+ SSLv2 altogether.
# WORKAROUND
* Some servers, notably Zimbra, return A1234 987 FETCH () in response to
session ID (this elaborate logic is designed to handle the case of
multiple names per userid gracefully).
+.IP \fBFETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE\fP
+(since v6.3.22):
+If this environment variable is set and not empty, fetchmail will disable
+a countermeasure against an SSL CBC IV attack (by setting
+SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS). This is a security risk, but may be
+necessary for connecting to certain non-standards-conforming servers.
+See fetchmail's NEWS file and fetchmail-SA-2012-01.txt for details.
+Earlier fetchmail versions (v6.3.21 and older) used to disable this
+countermeasure, but v6.3.22 no longer does that as a safety precaution.
+
.IP \fBFETCHMAIL_INCLUDE_DEFAULT_X509_CA_CERTS\fP
(since v6.3.17):
If this environment variable is set and not empty, fetchmail will always load
SSL_CTX_set_options(_ctx[sock], SSL_OP_ALL);
+ {
+ char *tmp = getenv("FETCHMAIL_DISABLE_CBC_IV_COUNTERMEASURE");
+ if (tmp == NULL || *tmp == '\0' || strspn(tmp, " \t") == strlen(tmp))
+ SSL_CTX_clear_options(_ctx[sock], SSL_OP_DONT_INSERT_EMPTY_FRAGMENTS);
+ }
+
if (certck) {
SSL_CTX_set_verify(_ctx[sock], SSL_VERIFY_PEER, SSL_ck_verify_callback);
} else {