lib/logmatcher.c in Balabit syslog-ng before 3.2.4, when the global flag is set and when using PCRE 8.12 and possibly other versions, allow…

published 2011-07-11 15 y ago modified 2026-06-16 4 mo ago also EUVD-2011-1945

cvss: 4.3; version 2.0, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 2.5%; EPSS 2.5% chance of exploitation in 30 days, percentile 84%
public exploits: 0; none known

lib/logmatcher.c in Balabit syslog-ng before 3.2.4, when the global flag is set and when using PCRE 8.12 and possibly other versions, allows remote attackers to cause a denial of service (memory consumption) via a message that does not match a regular expression.

Patch / fix

fixed in 3 distros 1 links 2

balabit syslog-ng 3.2.4
balabit syslog-ng_open_source_edition 3.2.4
oneidentity syslog-ng 3.2.4

syslog-ng Debian 14, Debian 13, Debian 12 3.2.4-1

debian advisories DEBIAN-CVE-2011-1951

bugzilla.redhat.com/show_bug.cgi?id=709088 advisory
openwall.com/lists/oss-security/2011/05/26/1 advisory

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2011-1951 updated 2025-11-21 cvss 4.3

syslog-ng: DoS (excessive memory use) by processing certain pcre patterns

Red Hat All currently supported Red Hat products
not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

Exploit prediction

2.46% chance of exploitation in the next 30 days, higher than 84% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by	version	score	vector
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:N/A:P

Classification

Weakness

CWE-399 Resource Management Errors

References

bugzilla.redhat.com /show_bug.cgi?id=709088
issue-tracking, patch, third-party-advisory
openwall.com /lists/oss-security/2011/05/26/1
mailing-list, patch, third-party-advisory
lists.fedoraproject.org /pipermail/package-announce/2011-June/062107.html
vendor-advisory, mailing-list, third-party-advisory
git.balabit.hu /?p=bazsi/syslog-ng-3.2.git%3Ba=commit%3Bh=09710c0b105e579d35c7b5f6c66d1ea5e3a3d3ff
securityfocus.com /bid/47800
vdb-entry, third-party-advisory
secunia.com /advisories/45122
third-party-advisory

Sources

CVE List CVE-2011-1951
NVD CVE-2011-1951

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Improved syslog-ng CPEs to better distinguish between opensource and premium product offerings.

Summary