The _gnutls_server_name_recv_params function in lib/ext_server_name.c in libgnutls in gnutls-serv in GnuTLS before 2.2.4 does not properly calculate the number of Server Names in a TLS 1.0 Client Hello message during extension handling, which allows remote attackers to cause a denial of service (crash) or possibly execute arbitrary code via a zero value for the length of Server Names, which leads to a buffer overflow in session resumption data in the pack_security_parameters function, aka GNUTLS-SA-2008-1-1.

From Red Hat Security Advisory 2008:0492 :

Updated gnutls packages that fix several security issues are now available for Red Hat Enterprise Linux 4.

This update has been rated as having important security impact by the Red Hat Security Response Team.

The GnuTLS Library provides support for cryptographic algorithms and protocols such as TLS. GnuTLS includes libtasn1, a library developed for ASN.1 structures management that includes DER encoding and decoding.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

We believe it is possible to leverage the flaw CVE-2008-1948 to execute arbitrary code but have been unable to prove this at the time of releasing this advisory. Red Hat Enterprise Linux 4 does not ship with any applications directly affected by this flaw. Third-party software which runs on Red Hat Enterprise Linux 4 could, however, be affected by this vulnerability. Consequently, we have assigned it important severity.

Users of GnuTLS are advised to upgrade to these updated packages, which contain a backported patch that corrects these issues.

From Red Hat Security Advisory 2008:0489 :

Updated gnutls packages that fix several security issues are now available for Red Hat Enterprise Linux 5.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

The GnuTLS Library provides support for cryptographic algorithms and protocols such as TLS. GnuTLS includes libtasn1, a library developed for ASN.1 structures management that includes DER encoding and decoding.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

We believe it is possible to leverage the flaw CVE-2008-1948 to execute arbitrary code but have been unable to prove this at the time of releasing this advisory. Red Hat Enterprise Linux 5 includes applications, such as CUPS, that would be directly vulnerable to any such an exploit, however. Consequently, we have assigned it critical severity.

Users of GnuTLS are advised to upgrade to these updated packages, which contain a backported patch that corrects these issues.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

At this time we have not seen any code that is using this exploit. But in Scientific Linux 5 there are some applications, such as CUPS, that would be directly vulnerable if/when there is an exploit. Because of the potential threat we are labeling this critical.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

At this time we have not seen any code that is using this exploit. But in Scientific Linux 5 there are some applications, that would be directly vulnerable if/when there is an exploit. Because of the potential threat we are labeling this important.

Updated gnutls packages that fix several security issues are now available for Red Hat Enterprise Linux 4.

This update has been rated as having important security impact by the Red Hat Security Response Team.

The GnuTLS Library provides support for cryptographic algorithms and protocols such as TLS. GnuTLS includes libtasn1, a library developed for ASN.1 structures management that includes DER encoding and decoding.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

We believe it is possible to leverage the flaw CVE-2008-1948 to execute arbitrary code but have been unable to prove this at the time of releasing this advisory. Red Hat Enterprise Linux 4 does not ship with any applications directly affected by this flaw. Third-party software which runs on Red Hat Enterprise Linux 4 could, however, be affected by this vulnerability. Consequently, we have assigned it important severity.

Users of GnuTLS are advised to upgrade to these updated packages, which contain a backported patch that corrects these issues.

Updated gnutls packages that fix several security issues are now available for Red Hat Enterprise Linux 5.

This update has been rated as having critical security impact by the Red Hat Security Response Team.

The GnuTLS Library provides support for cryptographic algorithms and protocols such as TLS. GnuTLS includes libtasn1, a library developed for ASN.1 structures management that includes DER encoding and decoding.

Flaws were found in the way GnuTLS handles malicious client connections. A malicious remote client could send a specially crafted request to a service using GnuTLS that could cause the service to crash. (CVE-2008-1948, CVE-2008-1949, CVE-2008-1950)

We believe it is possible to leverage the flaw CVE-2008-1948 to execute arbitrary code but have been unable to prove this at the time of releasing this advisory. Red Hat Enterprise Linux 5 includes applications, such as CUPS, that would be directly vulnerable to any such an exploit, however. Consequently, we have assigned it critical severity.

Users of GnuTLS are advised to upgrade to these updated packages, which contain a backported patch that corrects these issues.

Multiple issues have been fixed in gnutls. CVE-2008-1948 (GNUTLS-SA-2008-1-1), CVE-2008-1949 (GNUTLS-SA-2008-1-2) and CVE-2008-1950 (GNUTLS-SA-2008-1-3) have been assigned to this issue.

Flaws discovered in versions prior to 2.2.4 (stable) and 2.3.10 (development) of GnuTLS allow an attacker to cause denial of service (application crash), and maybe (so far undetermined) execute arbitrary code.

The updated packages have been patched to fix these flaws.

Note that any applications using this library must be restarted for the update to take effect.

Multiple issues have been fixed in gnutls: CVE-2008-1948 (GNUTLS-SA-2008-1-1), CVE-2008-1949 (GNUTLS-SA-2008-1-2) and CVE-2008-1950 (GNUTLS-SA-2008-1-3) have been assigned to this issue.

New gnutls packages are available for Slackware 12.0, 12.1, and
-current to fix security issues.

The version of VLC Media Player installed on the remote host reportedly includes versions of GnuTLS, libgcrypt, and libxml2 that are affected by various denial of service and buffer overflow vulnerabilities.

Multiple flaws were discovered in the connection handling of GnuTLS. A remote attacker could exploit this to crash applications linked against GnuTLS, or possibly execute arbitrary code with permissions of the application's user.

Note that Tenable Network Security has extracted the preceding description block directly from the Ubuntu security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

The remote host is affected by the vulnerability described in GLSA-200805-20 (GnuTLS: Execution of arbitrary code)

    Ossi Herrala and Jukka Taimisto of Codenomicon reported three     vulnerabilities in libgnutls of GnuTLS:
    'Client Hello' messages containing an invalid server name can lead to a     buffer overflow when evaluating 'Security Parameters' (CVE-2008-1948).
    Multiple 'Client Hello' messages can lead to a NULL pointer dereference     (CVE-2008-1949).
    A TLS handshake including an encrypted 'Client Hello' message and an     invalid record length could lead to a buffer overread (CVE-2008-1950).
  Impact :

    Unauthenticated remote attackers could exploit these vulnerabilities to     cause Denial of Service conditions in daemons using GnuTLS. The first     vulnerability (CVE-2008-1948) might allow for the execution of     arbitrary code with the privileges of the daemon handling incoming TLS     connections.
  Workaround :

    There is no known workaround at this time.

Fixes critical security issue GNUTLS-SA-2008-1 described here:
http://lists.gnu.org/archive/html/gnutls-devel/2008-05/msg00060.html All applications and system services which utilize gnutls library must be restarted for the updates to take effect.

Note that Tenable Network Security has extracted the preceding description block directly from the Fedora security advisory. Tenable has attempted to automatically clean and format it as much as possible without introducing additional issues.

Several remote vulnerabilities have been discovered in GNUTLS, an implementation of the SSL/TLS protocol suite.

NOTE: The libgnutls13 package, which provides the GNUTLS library, does not contain logic to automatically restart potentially affected services. You must restart affected services manually (mainly Exim, using '/etc/init.d/exim4 restart') after applying the update, to make the changes fully effective. Alternatively, you can reboot the system.

The Common Vulnerabilities and Exposures project identifies the following problems :

  - CVE-2008-1948     A pre-authentication heap overflow involving oversized     session resumption data may lead to arbitrary code     execution.

  - CVE-2008-1949     Repeated client hellos may result in a     pre-authentication denial of service condition due to a     NULL pointer dereference.

  - CVE-2008-1950     Decoding cipher padding with an invalid record length     may cause GNUTLS to read memory beyond the end of the     received record, leading to a pre-authentication denial     of service condition.

The version of VLC Media Player installed on the remote host reportedly includes versions of GnuTLS, libgcrypt and libxml2 that are affected by various denial of service and buffer overflow vulnerabilities.

ID	Name	Product	Family	Severity
67697	Oracle Linux 4 : gnutls (ELSA-2008-0492)	Nessus	Oracle Linux Local Security Checks	critical
67696	Oracle Linux 5 : gnutls (ELSA-2008-0489)	Nessus	Oracle Linux Local Security Checks	critical
60401	Scientific Linux Security Update : gnutls on SL5.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	critical
60400	Scientific Linux Security Update : gnutls on SL4.x i386/x86_64	Nessus	Scientific Linux Local Security Checks	critical
43689	CentOS 4 : gnutls (CESA-2008:0492)	Nessus	CentOS Local Security Checks	critical
43688	CentOS 5 : gnutls (CESA-2008:0489)	Nessus	CentOS Local Security Checks	critical
41514	SuSE 10 Security Update : GnuTLS (ZYPP Patch Number 5543)	Nessus	SuSE Local Security Checks	critical
41237	SuSE9 Security Update : GnuTLS (YOU Patch Number 12230)	Nessus	SuSE Local Security Checks	critical
37379	Mandriva Linux Security Advisory : gnutls (MDVSA-2008:106)	Nessus	Mandriva Local Security Checks	critical
34215	SuSE 10 Security Update : GnuTLS (ZYPP Patch Number 5601)	Nessus	SuSE Local Security Checks	critical
34214	openSUSE 10 Security Update : gnutls (gnutls-5275)	Nessus	SuSE Local Security Checks	critical
33288	Slackware 12.0 / 12.1 / current : gnutls (SSA:2008-180-01)	Nessus	Slackware Local Security Checks	critical
33278	VLC Media Player < 0.8.6h Multiple Vulnerabilities	Nessus	Windows	high
32432	Ubuntu 6.06 LTS / 7.04 / 7.10 / 8.04 LTS : gnutls12, gnutls13 vulnerabilities (USN-613-1)	Nessus	Ubuntu Local Security Checks	critical
32429	RHEL 4 : gnutls (RHSA-2008:0492)	Nessus	Red Hat Local Security Checks	critical
32428	RHEL 5 : gnutls (RHSA-2008:0489)	Nessus	Red Hat Local Security Checks	critical
32418	GLSA-200805-20 : GnuTLS: Execution of arbitrary code	Nessus	Gentoo Local Security Checks	critical
32414	Fedora 7 : gnutls-1.6.3-3.fc7 (2008-4274)	Nessus	Fedora Local Security Checks	critical
32412	Fedora 9 : gnutls-2.0.4-3.fc9 (2008-4259)	Nessus	Fedora Local Security Checks	critical
32408	Fedora 8 : gnutls-1.6.3-3.fc8 (2008-4183)	Nessus	Fedora Local Security Checks	critical
32403	Debian DSA-1581-1 : gnutls13 - several vulnerabilities	Nessus	Debian Local Security Checks	critical
4562	VLC Media Player < 0.8.6h Multiple Vulnerabilities (deprecated)	Nessus Network Monitor	Web Clients	high

Detections

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CVE-2008-1948

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