Patch Forecast
Amber warning
Patch this week.

CVE-2026-102555

Gnome Libsoup: out-of-bounds read can lead to denial of service

Risk score
60/100
CVSS
8.2 v3.1
Exploit chance (30 days)
0.4%
Published
29 Sep 2026

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What to know

What it is
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 r…
Affected
Gnome Libsoup
Fix
Apply the vendor's security update; see the linked advisory.
Exploitation
No known exploitation

Story map

Story map: Gnome LibsoupTHE FLAWSTHE FIXCVE-2026-102555Out-of-bounds read can lead todenial of serviceCVSS 8.2 · EPSS 0%CVE-2026-4271Use-after-free can lead todenial of serviceCVSS 7.5 · EPSS 1%CVE-2026-102560Out-of-bounds readCVSS 9.8 · EPSS 0%CVE-2026-5119A flaw was found in libsoupCVSS 8.2 · EPSS 0%FixCheck the linked advisory fordetails on the fix.Who is exposed{'products': ['libsoup'],'packages': [], 'versions': []}AMBER · PATCH THIS WEEKGnome LibsoupA Use-After-Free vulnerabilityin libsoup's HTTP/2 serverimplementation allows a remoteattacker to cause applicationinstability or crashes, resultingin a Denial of Service (DoS), bysending specially crafted…Where it standsPublic proof of conceptHOW IT UNFOLDEDOfficial record on the left, the press on the right, oldest first.21 Oct · Ubuntu security noticesUSN-8890-2: libsoup vulnerabilitiesCONNECTS TOSame weaknessOut-of-bounds read (CWE-125)372 other warnings in 30 days →Same productEarlier Gnome Libsoup warnings5 in the last 90 days →
Story map: the flaws, the fix, how it unfolded and what it connects to. Boxes link to the record or article.

At a glance

Gnome Libsoup: Amber, patch this week. A Use-After-Free vulnerability in libsoup's HTTP/2 server implementation allows a remote attacker to cause application instability or crashes, resulting in a Denial of Service (DoS), by sending specially crafted HTTP/2 requests.

The flaws

  • CVE-2026-102555: Out-of-bounds read can lead to denial of service (CVSS 8.2 · EPSS 0%)
  • CVE-2026-4271: Use-after-free can lead to denial of service (CVSS 7.5 · EPSS 1%)
  • CVE-2026-102560: Out-of-bounds read (CVSS 9.8 · EPSS 0%)
  • CVE-2026-5119: A flaw was found in libsoup (CVSS 8.2 · EPSS 0%)

The fix

Fix: Check the linked advisory for details on the fix.

Who is exposed: {'products': ['libsoup'], 'packages': [], 'versions': []}

Where it stands

  • Public proof of concept

How it unfolded

  1. 21 Oct, Ubuntu security notices (official): USN-8890-2: libsoup vulnerabilities

Connects to

Why it is Amber

  • CVSS 8.2 high
  • Remotely exploitable without logging in

References

Original 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.

Last activity 29 Sep 2026. Patch Forecast updates every hour.