After a failed cache insertion, addgetnetgrentX tries to send the non-existing response after the not-found header.

In addinnetgrX, addgetnetgrentX may have produced a NULL result, indicating a not-found status, but this is not handled in the subsequent code that prepares the record that will be sent out to the client.

Reference: https://sourceware.org/bugzilla/showbug.cgi?id=31678

After a failed cache insertion, addgetnetgrentX tries to send the non-existing response after the not-found header.

In addinnetgrX, addgetnetgrentX may have produced a NULL result, indicating a not-found status, but this is not handled in the subsequent code that prepares the record that will be sent out to the client.

Reference: https://sourceware.org/bugzilla/showbug.cgi?id=31678

Calling gethostbyaddr or gethostbyaddrr with a configured nsswitch.conf that specifies the library's DNS backend in the GNU C library version 2.34 to version 2.43 could result in an invalid DNS hostname being returned to the caller in violation of the DNS specification.

Last updated 30 June 2026

A flaw has been identified in glibc. In an extremely rare situation, the getaddrinfo function may access memory that has been freed, resulting in an application crash. This issue is only exploitable when a NSS module implements only the nssgethostbyname2r and nssgetcanonnamer hooks without implementing the nssgethostbyname3r hook. The resolved name should return a large number of IPv6 and IPv4, and the call to the getaddrinfo function should have the AFINET6 address family with AICANONNAME, AIALL and AIV4MAPPED as flags.

Calling NSS-backed functions that support caching via nscd may call the nscd client side code and in the GNU C Library version 2.36 under high load on x8664 systems, the client may call memcmp on inputs that are concurrently modified by other processes or threads and crash.

The nscd client in the GNU C Library uses the memcmp function with inputs that may be concurrently modified by another thread, potentially resulting in spurious cache misses, which in itself is not a security issue.  However in the GNU C Library version 2.36 an optimized implementation of memcmp was introduced for x8664 which could crash when invoked with such undefined behaviour, turning this into a potential crash of the nscd client and the application that uses it. This implementation was backported to the 2.35 branch, making the nscd client in that branch vulnerable as well.  Subsequently, the fix for this issue was backported to all vulnerable branches in the GNU C Library repository.

It is advised that distributions that may have cherry-picked the memcpy SSE2 optimization in their copy of the GNU C Library, also apply the fix to avoid the potential crash in the nscd client.

A flaw was found in glibc. When the getaddrinfo function is called with the AFUNSPEC address family and the system is configured with no-aaaa mode via /etc/resolv.conf, a DNS response via TCP larger than 2048 bytes can potentially disclose stack contents through the function returned address data, and may cause a crash.

Last updated 18 August 2025

The getifaddrs function in GNU libc (glibc) 2.2.4 and earlier allows local users to cause a denial of service by sending spoofed messages as other users to the kernel netlink interface.

In an extremely rare situation, the getaddrinfo function in glibc may access memory that has already been freed, resulting in an application crash.

This issue is only exploitable when a NSS module implements only the nssgethostbyname2r hook without implementing the nssgethostbyname3r hook. There are no known modules that are implemented in this way.

In addition to that condition, the resolved name should return a large number of IPv6 as well as IPv4 and the call to the getaddrinfo function should have AFINET6 with AICANONNAME, AIALL and AIV4MAPPED as flags.

Reference: https://sourceware.org/bugzilla/showbug.cgi?id=30843

A flaw has been identified in glibc. In an uncommon situation, the gaihinet function may use memory that has been freed, resulting in an application crash. This issue is only exploitable when the getaddrinfo function is called and the hosts database in /etc/nsswitch.conf is configured with SUCCESS=continue or SUCCESS=merge.

GNU C Library (glibc) is vulnerable to a denial of service, caused by an error in the iconv program. By processing invalid multi-byte input sequences, a remote attacker could exploit this vulnerability to cause the application to enter into an infinite loop.

Integer signedness error in the elfgetdynamicinfo function in elf/dynamic-link.h in ld.so in the GNU C Library (aka glibc or libc6) 2.0.1 through 2.11.1, when the --verify option is used, allows user-assisted remote attackers to execute arbitrary code via a crafted ELF program with a negative value for a certain dtag structure member in the ELF header.

Common Vulnerabilities and Exposures assigned an identifier CVE-2009-4880 to the following vulnerability:

Multiple integer overflows in the strfmon implementation in the GNU C Library (aka glibc or libc6) 2.10.1 and earlier allow context-dependent attackers to cause a denial of service (memory consumption or application crash) via a crafted format string, as demonstrated by a crafted first argument to the moneyformat function in PHP, a related issue to CVE-2008-1391.

References: [1] http://securityreason.com/achievementsecurityalert/67 [2] https://bugzilla.redhat.com/showbug.cgi?id=524671 [3] http://sources.redhat.com/bugzilla/showbug.cgi?id=10600 [4] http://sourceware.org/git/?p=glibc.git;a=commit;h=199eb0de8d673fb23aa127721054b4f1803d61f3 [5] http://www.ubuntu.com/usn/USN-944-1 [6] http://www.securityfocus.com/bid/36443 [7] http://secunia.com/advisories/39900 [8] http://www.vupen.com/english/advisories/2010/1246

Public PoC (from [3]):

[cx@localhost ~]$ php -r 'moneyformat("%.1073741821i",1);' Segmentation fault

Common Vulnerabilities and Exposures assigned an identifier CVE-2009-4881 to the following vulnerability:

Integer overflow in the vstrfmonl function in stdlib/strfmonl.c in the strfmon implementation in the GNU C Library (aka glibc or libc6) before 2.10.1 allows context-dependent attackers to cause a denial of service (application crash) via a crafted format string, as demonstrated by the %99999999999999999999n string, a related issue to CVE-2008-1391.

References: [1] http://sources.redhat.com/bugzilla/showbug.cgi?id=10600 [2] http://sourceware.org/git/?p=glibc.git;a=commit;h=153aa31b93be22e01b236375fb02a9f9b9a0195f [3] http://sources.redhat.com/bugzilla/showbug.cgi?id=10600 [4] http://securityreason.com/achievementsecurityalert/53 [5] http://xorl.wordpress.com/2009/04/11/cve-2008-1391-netbsd-strfmon-integer-overflow/

Public PoC (from [4]):

#include <stdio.h> #include <monetary.h>

int main(int argc, char argv[]){ char buff[51]; char bux=buff; int res;

res=strfmon(bux, 50, argv[1], "0"); return 0; }

cxib# ./pln %99999999999999999999n

If the system is configured in no-aaaa mode via /etc/resolv.conf, getaddrinfo is called for the AFUNSPEC address family, and a DNS response is received over TCP that is larger than 2048 bytes, getaddrinfo may potentially disclose stack contents via the returned address data, or crash. While name lookup normally just fails incorrectly, crashes are not difficult to trigger, with valid DNS responses that are propagated by DNS resolvers.

Reference: https://sourceware.org/bugzilla/showbug.cgi?id=30842

An insufficient entropy vulnerability was found in glibc. The getrandom and arc4random family of functions may return predictable randomness if these functions are called again after the fork, which happens concurrently with a call to any of these functions.

Common Vulnerabilities and Exposures assigned an identifier CVE-2010-4756 to the following vulnerability:

Name: CVE-2010-4756 URL: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2010-4756 Assigned: 20110302 Reference: http://securityreason.com/achievementsecurityalert/89 Reference: http://cxib.net/stuff/glob-0day.c Reference: http://securityreason.com/exploitalert/9223

The glob implementation in the GNU C Library (aka glibc or libc6) allows remote authenticated users to cause a denial of service (CPU and memory consumption) via crafted glob expressions that do not match any pathnames, as demonstrated by glob expressions in STAT commands to an FTP daemon, a different vulnerability than CVE-2010-2632.

Last updated 24 July 2024

Last updated 24 July 2024

Last updated 25 August 2025

DISPUTED GNU Libc current is affected by: Mitigation bypass. The impact is: Attacker may guess the heap addresses of pthreadcreated thread. The component is: glibc. NOTE: the vendor's position is "ASLR bypass itself is not a vulnerability."

DISPUTED GNU Libc current is affected by: Mitigation bypass. The impact is: Attacker may bypass ASLR using cache of thread stack and heap. The component is: glibc. NOTE: Upstream comments indicate "this is being treated as a non-security bug and no real threat."

It was reported that if a process that called glibc's svcrun() exceeded the limit of opened files for a longer period of time, that accept() in rendezvousrequest()/svcudprecv() would fail with the EMFILE error, which would lead to looping between poll(), accept(), and 'for' loops which would consume a lot of CPU time. This could lead to an unresponsive system that requires human intervention (service restart or system restart) to resolve.

The Sun RPC functionality in multiple libc implementations does not provide a time-out mechanism when reading data from TCP connections, which allows remote attackers to cause a denial of service (hang).

The BIND 4 and BIND 8.2.x stub resolver libraries, and other libraries such as glibc 2.2.5 and earlier, libc, and libresolv, use the maximum buffer size instead of the actual size when processing a DNS response, which causes the stub resolvers to read past the actual boundary ("read buffer overflow"), allowing remote attackers to cause a denial of service (crash).

The nscd daemon in the GNU C Library (glibc) before version 2.5 does not close incoming client sockets if they cannot be handled by the daemon, allowing local users to carry out a denial of service attack on the daemon.

Stack consumption vulnerability in the regcomp implementation in the GNU C Library (aka glibc or libc6) through 2.11.3, and 2.12.x through 2.12.2, allows context-dependent attackers to cause a denial of service (resource exhaustion) via a regular expression containing adjacent repetition operators, as demonstrated by a {10,}{10,}{10,}{10,} sequence in the proftpd.gnu.c exploit for ProFTPD.

Maksymilian Arciemowicz reported a deficiency in the way glibc regular expression engine processed certain patterns. A local attacker could use this flaw to cause a denial of service (crash due stack overflow).

Note: The above described behavior is a limitation of glibc regular expression engine. Regular expression matching function is called recursively for certain types of patterns (where subexpression using quantifier is nested inside of another quantified expression), where long input can result in deep recursion and exhaustion of all stack memory (i.e. impact is limited to crash). Amount of stack memory available to glibc regular expression engine influences the size of input that must be provided to trigger the crash. Alternatively, expression can be modified to avoid quantification nesting, or program modified to limit size of input passed to regular expression engine.

Conclusion: Due the above described behavior Red Hat Security Response Team would not classify this deficiency to be a security issue.

References: [1] http://www.kb.cert.org/vuls/id/912279 [2] http://www.securityfocus.com/archive/1/515589 [3] http://forums.cnet.com/7726-6132102-5042238.html [4] http://secunia.com/advisories/42547/ [5] http://securityreason.com/securityalert/8003

A security flaw was found in the way strcoll() interface of glibc, the GNU libc libraries, performed failsafe back to alloca() routine when malloc() function call failed previously (due to out of memory [OOM] condition for example). If an application linked against glibc was missing an application-level sanity checks for validity of strcoll() arguments and accepted untrusted input, an attacker could use this flaw to cause the particular application to crash or, potentially, execute arbitrary code with the privileges of the user running the application.

Upstream bug report (including the reproducer): [1] http://sourceware.org/bugzilla/showbug.cgi?id=14552#c0

Issue / part: 1) alloca() stack overflow from [1].

References: [2] http://www.openwall.com/lists/oss-security/2012/09/07/9 [3] http://www.openwall.com/lists/oss-security/2012/09/07/15 [4] http://www.openwall.com/lists/oss-security/2012/09/10/1 [5] http://www.openwall.com/lists/oss-security/2012/09/10/3 [6] http://www.openwall.com/lists/oss-security/2012/09/13/16