# CVE-2026-1484: GNOME GLib integer overflow in Base64 encoding

Source: https://junglewise.ai/threats/cve-2026-1484-gnome-glib-integer-overflow-in-base64-encoding  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-01-27. Updated: 2026-06-02  
License: CC BY 4.0 with a link back

CVE-2026-1484 · Severity: medium · CVSS 4.2 · Published 2026-01-27

A vulnerability exists in GLib, a widely used low-level software library, specifically within its Base64 encoding functionality. If an application uses this library to process extremely large amounts of data (gigabytes in size) provided by a user, it could lead to a system crash or unpredictable behavior. This could potentially be used by an attacker to disrupt services or, in complex scenarios, gain unauthorized access to memory.

Technologies: [Gnome Glib](https://junglewise.ai/threats/technologies/glib), [Siemens RUGGEDCOM RST2428P](https://junglewise.ai/threats/technologies/ruggedcom-rst2428p), [Siemens SINEC OS](https://junglewise.ai/threats/technologies/sinec-os). Vendors: [Gnome](https://junglewise.ai/threats/vendors/gnome), [Siemens](https://junglewise.ai/threats/vendors/siemens).

## Quick answers

**Is CVE-2026-1484 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-1484 being exploited in the wild.

**How severe is CVE-2026-1484?** Medium severity, with a CVSS score of 4.2, published 27 January 2026.

**Which products and versions are affected?** Gnome Glib through 2.87.0; Siemens RUGGEDCOM RST2428P before V4.0; Siemens SINEC OS before V4.0.

**Is there a fix for CVE-2026-1484?** A patch was published on 2026-06-02: Siemens released SINEC OS V4.0 addressing the issue in industrial products Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-1484 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-1484?** Check whether you run Gnome Glib, Siemens RUGGEDCOM RST2428P or Siemens SINEC OS 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 leading to a buffer underflow exists in GLib's g_base64_encode() function. The vulnerability is caused by storing the output length returned by g_base64_encode_step() in a signed integer (gint) instead of a size_t (gsize). When encoding attacker-controlled input of approximately 2GB or more, the signed integer overflows and becomes negative. This negative value is subsequently used in pointer arithmetic within g_base64_encode_close(), resulting in a heap-based out-of-bounds write. An attacker can exploit this to cause a denial of service (crash) or potentially achieve memory corruption. The issue was identified in glib/gbase64.c and affects versions up to 2.87.0.

## Affected products

- GNOME GLib through 2.87.0
- Siemens SINEC OS before V4.0
- Siemens RUGGEDCOM RST2428P before V4.0

## Timeline

- 2025-12-16: disclosed: Reported to GNOME via YesWeHack
- 2026-01-27: advisory: Initial CVE publication and Red Hat advisory
- 2026-06-02: patched: Siemens released SINEC OS V4.0 addressing the issue in industrial products

## References

- [https://access.redhat.com/security/cve/CVE-2026-1484](https://access.redhat.com/security/cve/CVE-2026-1484)
- [https://bugzilla.redhat.com/show_bug.cgi?id=2433259](https://bugzilla.redhat.com/show_bug.cgi?id=2433259)
- [https://gitlab.gnome.org/GNOME/glib/-/issues/3870](https://gitlab.gnome.org/GNOME/glib/-/issues/3870)
- [https://cert-portal.siemens.com/productcert/html/ssa-253495.html](https://cert-portal.siemens.com/productcert/html/ssa-253495.html)

## Related threats

- [GNOME GLib denial of service in GDBus authentication](https://junglewise.ai/threats/cve-2026-15588-gnome-glib-denial-of-service-in-gdbus-authentication)
- [GNOME GLib out-of-bounds read in D-Bus introspection XML parsing](https://junglewise.ai/threats/cve-2026-58016-gnome-glib-out-of-bounds-read-in-d-bus-introspection-xml-parsing)
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- [GNOME GLib off-by-one error in g_key_file_get_locale_string_list](https://junglewise.ai/threats/cve-2026-58014-gnome-glib-off-by-one-error-in-g-key-file-get-locale-string-list)
- [GNOME GLib buffer over-read in g_io_channel_read_line_backend](https://junglewise.ai/threats/cve-2026-58013-gnome-glib-buffer-over-read-in-g-io-channel-read-line-backend)