What is CVE-2011-1720?

CVE-2011-1720 is a vulnerability in Postfix, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2011-05-13.

Is CVE-2011-1720 known to be exploited?

8 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Buffer overflow in Postfix

CVE-2011-1720

The SMTP server in Postfix before 2.5.13, 2.6.x before 2.6.10, 2.7.x before 2.7.4, and 2.8.x before 2.8.3, when certain Cyrus SASL authentication methods are enabled, does not create a new server handle after client authentication fails, which allows remote attackers to cause a denial of service (heap memory corruption and daemon crash) or possibly execute arbitrary code via an invalid AUTH command with one method followed by an AUTH command with a different method.

Vulnerability class: Buffer Overflow

Published 2011-05-13 · last modified 2026-06-16.

CVSS v2 metric

CVSS v2 base score 6.8 (Medium). Vector: AV:N/AC:M/Au:N/C:P/I:P/A:P. This CVE predates CVSS v3 and has no v3 score from NVD.

EPSS exploit prediction

EPSS: 0.215 (97.5th percentile), scored 2026-10-01.

Moderate probability of exploitation in the next 30 days — watch for active exploitation reports. 98th percentile — 97.5% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.215 · newest: 0.215 · change: 0.000

Affected products

Postfix — versions 2.0.0, 2.0.1, 2.0.2

Weakness classification (CWE)

CWE-119 — Improper Restriction of Operations within the Bounds of a Memory Buffer

Public proof-of-concept exploits

References

www.securityfocus.com/archive/1/517917/100/0/threaded (mailing-list)
www.postfix.org/CVE-2011-1720.html (Vendor Advisory)
secunia.com/advisories/44500 (Vendor Advisory, third-party-advisory)
www.securityfocus.com/bid/47778 (Patch, vdb-entry)
security.gentoo.org/glsa/glsa-201206-33.xml (vendor-advisory)
www.osvdb.org/72259 (vdb-entry)
www.kb.cert.org/vuls/id/727230 (US Government Resource, third-party-advisory)
www.securitytracker.com/id (vdb-entry)
www.mail-archive.com/postfix-announce@postfix.org/msg00007.html (mailing-list)
www.postfix.org/announcements/postfix-2.8.3.html (Vendor Advisory)

Frequently asked questions

What is CVE-2011-1720?: CVE-2011-1720 is a vulnerability in Postfix, classified under Improper Restriction of Operations within the Bounds of a Memory Buffer. Published 2011-05-13.
Is CVE-2011-1720 known to be exploited?: 8 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.