Rsyslog is a rocket-fast system for log processing. Modules for TCP syslog reception have a potential heap buffer overflow when octet-counted framing is used. This can result in a segfault or some other malfunction. As of our understanding, this vulnerability can not be used for remote code execution. But there may still be a slight chance for experts to do that. The bug occurs when the octet count is read. While there is a check for the maximum number of octets, digits are written to a heap buffer even when the octet count is over the maximum, This can be used to overrun the memory buffer. However, once the sequence of digits stop, no additional characters can be added to the buffer. In our opinion, this makes remote exploits impossible or at least highly complex. Octet-counted framing is one of two potential framing modes. It is relatively uncommon, but enabled by default on receivers. Modules `imtcp`, `imptcp`, `imgssapi`, and `imhttp` are used for regular syslog message reception. It is best practice not to directly expose them to the public. When this practice is followed, the risk is considerably lower. Module `imdiag` is a diagnostics module primarily intended for testbench runs. We do not expect it to be present on any production installation. Octet-counted framing is not very common. Usually, it needs to be specifically enabled at senders. If users do not need it, they can turn it off for the most important modules. This will mitigate the vulnerability.
Max CVSS
8.1
EPSS Score
10.74%
Published
2022-05-06
Updated
2023-06-23
An issue was discovered in Rsyslog v8.1908.0. contrib/pmcisconames/pmcisconames.c has a heap overflow in the parser for Cisco log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon), but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The message will then be considered valid, and the parser will eat up the nonexistent colon delimiter. In doing so, it will decrement lenMsg, a signed integer, whose value was zero and now becomes minus one. The following step in the parser is to shift left the contents of the message. To do this, it will call memmove with the right pointers to the target and destination strings, but the lenMsg will now be interpreted as a huge value, causing a heap overflow.
Max CVSS
9.8
EPSS Score
0.67%
Published
2019-10-07
Updated
2021-12-06
An issue was discovered in Rsyslog v8.1908.0. contrib/pmaixforwardedfrom/pmaixforwardedfrom.c has a heap overflow in the parser for AIX log messages. The parser tries to locate a log message delimiter (in this case, a space or a colon) but fails to account for strings that do not satisfy this constraint. If the string does not match, then the variable lenMsg will reach the value zero and will skip the sanity check that detects invalid log messages. The message will then be considered valid, and the parser will eat up the nonexistent colon delimiter. In doing so, it will decrement lenMsg, a signed integer, whose value was zero and now becomes minus one. The following step in the parser is to shift left the contents of the message. To do this, it will call memmove with the right pointers to the target and destination strings, but the lenMsg will now be interpreted as a huge value, causing a heap overflow.
Max CVSS
9.8
EPSS Score
0.71%
Published
2019-10-07
Updated
2021-12-06
contrib/pmdb2diag/pmdb2diag.c in Rsyslog v8.1908.0 allows out-of-bounds access because the level length is mishandled.
Max CVSS
9.8
EPSS Score
0.57%
Published
2019-09-30
Updated
2019-10-07
A denial of service vulnerability was found in rsyslog in the imptcp module. An attacker could send a specially crafted message to the imptcp socket, which would cause rsyslog to crash. Versions before 8.27.0 are vulnerable.
Max CVSS
7.5
EPSS Score
2.83%
Published
2019-01-25
Updated
2022-10-06
The zmq3 input and output modules in rsyslog before 8.28.0 interpreted description fields as format strings, possibly allowing a format string attack with unspecified impact.
Max CVSS
9.8
EPSS Score
0.28%
Published
2017-08-06
Updated
2017-08-14
rsyslog uses weak permissions for generating log files, which allows local users to obtain sensitive information by reading files in /var/log/cron.
Max CVSS
5.5
EPSS Score
0.04%
Published
2017-07-25
Updated
2017-07-31
Integer overflow in rsyslog before 7.6.7 and 8.x before 8.4.2 and sysklogd 1.5 and earlier allows remote attackers to cause a denial of service (crash) via a large priority (PRI) value. NOTE: this vulnerability exists because of an incomplete fix for CVE-2014-3634.
Max CVSS
5.0
EPSS Score
12.65%
Published
2014-11-02
Updated
2016-10-18
rsyslog before 7.6.6 and 8.x before 8.4.1 and sysklogd 1.5 and earlier allows remote attackers to cause a denial of service (crash), possibly execute arbitrary code, or have other unspecified impact via a crafted priority (PRI) value that triggers an out-of-bounds array access.
Max CVSS
7.5
EPSS Score
22.67%
Published
2014-11-02
Updated
2016-10-18
Double free vulnerability in the writeDataError function in the ElasticSearch plugin (omelasticsearch) in rsyslog before 7.4.2 and before 7.5.2 devel, when errorfile is set to local logging, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted JSON response.
Max CVSS
6.8
EPSS Score
1.29%
Published
2013-10-04
Updated
2013-10-07
Integer overflow in the rsCStrExtendBuf function in runtime/stringbuf.c in the imfile module in rsyslog 4.x before 4.6.6, 5.x before 5.7.4, and 6.x before 6.1.4 allows local users to cause a denial of service (daemon hang) via a large file, which triggers a heap-based buffer overflow.
Max CVSS
2.1
EPSS Score
0.04%
Published
2012-09-25
Updated
2023-02-13

CVE-2011-3200

Public exploit
Stack-based buffer overflow in the parseLegacySyslogMsg function in tools/syslogd.c in rsyslogd in rsyslog 4.6.x before 4.6.8 and 5.2.0 through 5.8.4 might allow remote attackers to cause a denial of service (application exit) via a long TAG in a legacy syslog message.
Max CVSS
5.0
EPSS Score
14.26%
Published
2011-09-06
Updated
2011-09-23
A memory leak in rsyslog before 5.7.6 was found in the way deamon processed log messages are logged when multiple rulesets were used and some output batches contained messages belonging to more than one ruleset. A local attacker could cause denial of the rsyslogd daemon service via a log message belonging to more than one ruleset
Max CVSS
5.5
EPSS Score
0.04%
Published
2019-11-14
Updated
2020-08-18
A memory leak in rsyslog before 5.7.6 was found in the way deamon processed log messages were logged when multiple rulesets were used and some output batches contained messages belonging to more than one ruleset. A local attacker could cause denial of the rsyslogd daemon service via a log message belonging to more than one ruleset.
Max CVSS
5.5
EPSS Score
0.04%
Published
2019-11-14
Updated
2020-08-18
A memory leak in rsyslog before 5.7.6 was found in the way deamon processed log messages are logged when $RepeatedMsgReduction was enabled. A local attacker could use this flaw to cause a denial of the rsyslogd daemon service by crashing the service via a sequence of repeated log messages sent within short periods of time.
Max CVSS
5.5
EPSS Score
0.04%
Published
2019-11-14
Updated
2020-08-18
imudp in rsyslog 4.x before 4.1.2, 3.21 before 3.21.9 beta, and 3.20 before 3.20.2 generates a message even when it is sent by an unauthorized sender, which allows remote attackers to cause a denial of service (disk consumption) via a large number of spurious messages.
Max CVSS
5.0
EPSS Score
0.16%
Published
2008-12-17
Updated
2008-12-17
The ACL handling in rsyslog 3.12.1 to 3.20.0, 4.1.0, and 4.1.1 does not follow $AllowedSender directive, which allows remote attackers to bypass intended access restrictions and spoof log messages or create a large number of spurious messages.
Max CVSS
8.5
EPSS Score
1.30%
Published
2008-12-17
Updated
2017-08-08
17 vulnerabilities found
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