# CVE-2023-6780: GNU glibc integer overflow in __vsyslog_internal

Source: https://junglewise.ai/threats/cve-2023-6780-gnu-glibc-integer-overflow-in-vsyslog-internal  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2024-01-31. Updated: 2026-05-12  
License: CC BY 4.0 with a link back

CVE-2023-6780 · Severity: medium · CVSS 5.3 · Published 2024-01-31

A vulnerability exists in the standard GNU C Library (glibc), a fundamental component used by almost all Linux-based systems. An attacker can exploit this flaw by providing an extremely long program name or message to the system's logging functions. This can lead to a system crash or, in some cases, allow a local user to gain full administrative (root) privileges on the machine.

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

## Quick answers

**Is CVE-2023-6780 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2023-6780 being exploited in the wild.

**How severe is CVE-2023-6780?** Medium severity, with a CVSS score of 5.3, published 31 January 2024.

**Which products and versions are affected?** Gnu Glibc 2.37, 2.38.

**Is there a fix for CVE-2023-6780?** A patch was published on 2024-01-31: Fedora 39 update released with fix in glibc 2.38-16 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2023-6780 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2023-6780?** 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

An integer overflow vulnerability exists in the __vsyslog_internal function within glibc, which is internally called by syslog() and vsyslog(). The flaw occurs when the function calculates the buffer size required for a log message; if the message (specifically the program name/argv[0]) is sufficiently large (e.g., >1024 bytes), the size calculation overflows, leading to a 1-byte heap allocation that is subsequently overflowed with attacker-controlled data. While the CVSS vector suggests network reachability, security researchers have demonstrated that it is primarily a local privilege escalation (LPE) vector, successfully exploiting SUID-root binaries like 'su' to gain root access. The issue affects glibc versions 2.37 and 2.38, and was fixed in version 2.39.

## Affected products

- GNU glibc 2.37, 2.38

## Timeline

- 2023-12-13: disclosed: Initial report to Red Hat Bugzilla
- 2024-01-30: advisory: Qualys security advisory published
- 2024-01-31: patched: Fedora 39 update released with fix in glibc 2.38-16

## References

- [http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html](http://packetstormsecurity.com/files/176932/glibc-syslog-Heap-Based-Buffer-Overflow.html)
- [http://seclists.org/fulldisclosure/2024/Feb/3](http://seclists.org/fulldisclosure/2024/Feb/3)
- [https://access.redhat.com/security/cve/CVE-2023-6780](https://access.redhat.com/security/cve/CVE-2023-6780)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2254396](https://bugzilla.redhat.com/show_bug.cgi?id=2254396)
- [https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D2FIH77VHY3KCRROCXOT6L27WMZXSJ2G/](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/D2FIH77VHY3KCRROCXOT6L27WMZXSJ2G/)
- [https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWQ6BZJ6CV5UAW4VZSKJ6TO4KIW2KWAQ/](https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/MWQ6BZJ6CV5UAW4VZSKJ6TO4KIW2KWAQ/)
- [https://security.gentoo.org/glsa/202402-01](https://security.gentoo.org/glsa/202402-01)

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