# CVE-2023-4806: GNU glibc use-after-free in getaddrinfo

Source: https://junglewise.ai/threats/cve-2023-4806-gnu-glibc-use-after-free-in-getaddrinfo  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2023-09-18. Updated: 2026-05-12  
License: CC BY 4.0 with a link back

CVE-2023-4806 · Severity: medium · CVSS 5.9 · Published 2023-09-18

A vulnerability has been found in the core system library (glibc) used by almost all Linux-based applications to translate web addresses into IP addresses. In specific, rare configurations, this flaw can cause an application to crash when it looks up a network address. While difficult to trigger, a successful exploit could lead to a denial-of-service, impacting the availability of critical system services and applications.

Technologies: [Gnu Glibc](https://junglewise.ai/threats/technologies/glibc). Vendors: [Gnu](https://junglewise.ai/threats/vendors/gnu).

## Quick answers

**Is CVE-2023-4806 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2023-4806 being exploited in the wild.

**How severe is CVE-2023-4806?** Medium severity, with a CVSS score of 5.9, published 18 September 2023.

**Which products and versions are affected?** Gnu Glibc 2.34-100.el9 and earlier.

**Is there a fix for CVE-2023-4806?** A patch was published on 2023-10-05: Red Hat released security updates for RHEL 9 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2023-4806 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2023-4806?** Check whether you run Gnu Glibc at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

A use-after-free (UAF) vulnerability exists in the glibc 'getaddrinfo' function. The flaw is triggered when a Name Service Switch (NSS) module implements only the '_nss_*_gethostbyname2_r' and '_nss_*_getcanonname_r' hooks, but lacks the '_nss_*_gethostbyname3_r' hook. For an exploit to occur, the resolved name must return a large number of IPv4 and IPv6 addresses, and the 'getaddrinfo' call must use specific flags (AF_INET6 with AI_CANONNAME, AI_ALL, and AI_V4MAPPED). An attacker who can influence DNS responses or name resolution results could potentially trigger this UAF to cause a denial-of-service (crash). Patches are available through major Linux distributions including Red Hat and Fedora.

## Affected products

- GNU glibc 2.34-100.el9 and earlier
- Red Hat Enterprise Linux 9 9.2, 9.4, 9.6

## Timeline

- 2023-09-18: disclosed
- 2023-10-05: patched: Red Hat released security updates for RHEL 9

## References

- [https://access.redhat.com/errata/RHBA-2024:2413](https://access.redhat.com/errata/RHBA-2024:2413)
- [https://access.redhat.com/errata/RHSA-2023:5453](https://access.redhat.com/errata/RHSA-2023:5453)
- [https://access.redhat.com/errata/RHSA-2023:5455](https://access.redhat.com/errata/RHSA-2023:5455)
- [https://access.redhat.com/errata/RHSA-2023:7409](https://access.redhat.com/errata/RHSA-2023:7409)
- [https://access.redhat.com/security/cve/CVE-2023-4806](https://access.redhat.com/security/cve/CVE-2023-4806)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2237782](https://bugzilla.redhat.com/show_bug.cgi?id=2237782)
- [http://www.openwall.com/lists/oss-security/2023/10/03/4](http://www.openwall.com/lists/oss-security/2023/10/03/4)

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