Description
The idnsGrokReply function in Squid before 3.1.16 does not properly free memory, which allows remote attackers to cause a denial of service (daemon abort) via a DNS reply containing a CNAME record that references another CNAME record that contains an empty A record.
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 6.0 | squid3 | 3.1.6-1.2+squeeze2 | DSA-2381-1 |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 6 | squid | 7:3.1.10-1.el6_2.1 | RHSA-2011:1791 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 11 SP4 | squid3 | 3.1.23-8.16.30.1 | SUSE-SU-2016:2089-1 |
Show 1 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 11 SP4 | squid3 | 3.1.23-8.16.30.1 | SUSE-SU-2016:2089-1 |
Advisories 3
- RHSA-2011:1791 Red Hat Security Advisory: squid security update Red Hat Security Advisories (RHSA) · Jun 26, 2026
- DSA-2381-1 squid3 - invalid memory deallocation Debian Security (DSA / DLA) · Mar 9, 2026
- SUSE-SU-2016:2089-1 Security update for squid3 SUSE / openSUSE Security Updates · Feb 4, 2026
References
- http://bugs.squid-cache.org/show_bug.cgi?id=3237#c12
- RHSA-2011:1791 vendor-advisory
- SUSE-SU-2016:1996 vendor-advisory
- [oss-security] 20111031 CVE Request -- Squid v3.1.16 -- Invalid free by processing CNAME DNS record pointing to another CNAME record pointing to an empty A-record mailing-list
- 1026265 vdb-entry
- [oss-security] 20111031 Re: CVE Request -- Squid v3.1.16 -- Invalid free by processing CNAME DNS record pointing to another CNAME record pointing to an empty A-record mailing-list
- MDVSA-2011:193 vendor-advisory
- 46609 third-party-advisory
- http://www.squid-cache.org/Versions/v3/3.1/changesets/SQUID_3_1_16.html
- SUSE-SU-2016:2089 vendor-advisory
- 47459 third-party-advisory