-----BEGIN PGP SIGNED MESSAGE-----
AUSCERT External Security Bulletin Redistribution
ESB-2000.097 -- FreeBSD-SA-00:08 [REVISED]
Lynx ports contain numerous buffer overflows
18 May 2000
AusCERT Security Bulletin Summary
Operating System: FreeBSD
Impact: Execute Arbitrary Code
Access Required: Remote
- --------------------------BEGIN INCLUDED TEXT--------------------
- -----BEGIN PGP SIGNED MESSAGE-----
FreeBSD-SA-00:08 Security Advisory
Topic: Lynx ports contain numerous buffer overflows
Affects: Ports collection before the correction date.
Corrected: 2000-04-16 [lynx-current]
FreeBSD only: NO
Lynx is a popular text-mode WWW browser, available in several versions
including SSL support and Japanese language localization.
II. Problem Description
Versions of the lynx software prior to version 2.8.3pre.5 were written
in a very insecure style and contain numerous potential and several
proven security vulnerabilities (publicized on the BugTraq mailing
list) exploitable by a malicious server.
The lynx ports are not installed by default, nor are they "part of
FreeBSD" as such: they are part of the FreeBSD ports collection, which
contains over 3200 third-party applications in a ready-to-install
FreeBSD makes no claim about the security of these third-party
applications, although an effort is underway to provide a security
audit of the most security-critical ports.
A malicious server which is visited by a user with the lynx browser
can exploit the browser security holes in order to execute arbitrary
code as the local user.
If you have not chosen to install any of the
then your system is not vulnerable.
Remove the lynx/lynx-current/lynx-ssl/ja-lynx/ja-lynx-current ports,
if you you have installed them.
Upgrade to lynx or lynx-current after the correction date.
After the initial release of this advisory, the Lynx development team
conducted an audit of the source code, and have corrected the known
vulnerabilities in lynx as well as increasing the robustness of the
string-handling code. As of lynx-2.8.3pre.5, we consider it safe
enough to use again.
Note that there may be undiscovered vulnerabilities remaining in the
code, as with all software - but should any further vulnerabilities be
discovered a new advisory will be issued.
At this time the lynx-ssl/ja-lynx/ja-lynx-current ports are not yet
updated to a safe version of lynx: this advisory will be reissued
again once they are.
1) Upgrade your entire ports collection and rebuild the lynx or
2) Reinstall a lynx new package dated after the correction date,
Note that the lynx-current port is not automatically built as a package.
3) download a new port skeleton for the lynx/lynx-current port from:
and use it to rebuild the port.
4) Use the portcheckout utility to automate option (3) above. The
portcheckout port is available in /usr/ports/devel/portcheckout or the
package can be obtained from:
VI. Revision History
v1.0 2000-03-15 Initial release
v1.1 2000-05-17 Update to note fix of lynx and lynx-current ports.
- -----BEGIN PGP SIGNATURE-----
- -----END PGP SIGNATURE-----
- --------------------------END INCLUDED TEXT--------------------
This security bulletin is provided as a service to AusCERT's members. As
AusCERT did not write the document quoted above, AusCERT has had no control
over its content. The decision to use any or all of this information is
the responsibility of each user or organisation, and should be done so in
accordance with site policies and procedures.
NOTE: This is only the original release of the security bulletin. It may
not be updated when updates to the original are made. If downloading at
a later date, it is recommended that the bulletin is retrieved directly
from the original authors to ensure that the information is still current.
Contact information for the authors of the original document is included
in the Security Bulletin above. If you have any questions or need further
information, please contact them directly.
Previous advisories and external security bulletins can be retrieved from:
If you believe that your system has been compromised, contact AusCERT or
your representative in FIRST (Forum of Incident Response and Security
Internet Email: email@example.com
Facsimile: (07) 3365 7031
Telephone: (07) 3365 4417 (International: +61 7 3365 4417)
AusCERT personnel answer during Queensland business hours
which are GMT+10:00 (AEST).
On call after hours for emergencies.
-----BEGIN PGP SIGNATURE-----
-----END PGP SIGNATURE-----