What’s Vulnerable › Vulnerabilities

CVE-2026-102555: Libsoup: libsoup: heap buffer overflow via uninitialized length in data-uri base64 decoding

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-09-29 · updated 2026-10-15
• Weakness: CWE-125

Description

A flaw was found in libsoup. The soup_uri_decode_data_uri() function incorrectly treated base64 data-URI payloads as NUL-terminated strings when calling g_base64_decode_inplace(). If the percent-decoded payload contained embedded NUL bytes, the decoded length could remain uninitialized and be used as the size of the returned GBytes. This can lead to an out-of-bounds read or application crash when processing a crafted data URI.

Affected products

• GNOME libsoup: before 3.7.3 — fixed in 3.7.3
• Red Hat Enterprise Linux: 9.0, 10.0

How to fix

Upgrade to a fixed version: GNOME libsoup 3.7.3. Check the vendor advisory for mitigations.

References

• https://access.redhat.com/errata/RHSA-2026:83618
• https://access.redhat.com/security/cve/CVE-2026-102555
• https://bugzilla.redhat.com/show_bug.cgi?id=2543224

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