Bug 2433259 (CVE-2026-1484)

Summary: CVE-2026-1484 Glib: Integer Overflow Leading to Buffer Underflow and Out-of-Bounds Write in GLib g_base64_encode()
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: adudiak, kshier, stcannon, teagle, yguenane
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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Doc Text:
A flaw was found in the GLib Base64 encoding routine when processing very large input data. Due to incorrect use of integer types during length calculation, the library may miscalculate buffer boundaries. This can cause memory writes outside the allocated buffer. Applications that process untrusted or extremely large Base64 input using GLib may crash or behave unpredictably.
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
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Bug Depends On: 2433260, 2433261, 2433262, 2433263, 2433264, 2433265, 2433266, 2433267, 2433268, 2433269, 2433270, 2433271, 2433272, 2433273, 2433274, 2433275, 2433276, 2433277, 2433278, 2433279, 2433280, 2433281, 2433282, 2433283, 2433284, 2433285, 2433286, 2433287, 2433288, 2433289, 2433290, 2433291, 2433292, 2433293, 2433294, 2433295, 2433296, 2433297, 2433300, 2433301, 2433302, 2433303, 2433304, 2433305, 2433306, 2433307, 2433308, 2433309, 2433310, 2433311, 2433312, 2433313, 2433314, 2433315, 2433318, 2433319, 2433320, 2433321    
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Description OSIDB Bzimport 2026-01-27 12:19:40 UTC 
Integer Overflow leads to Buffer Underflow vulnerability in GLib’s Base64 encoding implementation. The flaw is caused by storing the output length returned by g_base64_encode_step() in a signed integer (gint). When encoding very large attacker-controlled input, this value may overflow and become negative. The resulting pointer arithmetic in g_base64_encode_close() leads to a buffer underflow and out-of-bounds heap write. Exploitation requires that an application passes untrusted or excessively large input to the Base64 encoding API and may result in application crashes or potential memory corruption.