Flatpak: The OCI delta stream parser read sizes as guint64 but passed them to GLib I/O and allocation functions
Affects flatpakSource GCVE Database
Not known to be exploited · CVSS 7.5 High.
Data as of 5 Nov 2026, 00:01 UTC
Thin evidence
One scorer or none| CNA (redhat) | CVSS 3.1 | 7.5 |
|---|
- EPSS
- 0.5% chance of exploitation in 30 days – higher than 48% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:HExploitation evidence
Disclosed: evidence found.
CVE published 27 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 4 Nov 2026.
What to do
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 26.04 LTSflatpakpkg:deb/ubuntu/flatpak?arch=source&distro=resoluteOther threats | Affected
| Fixed in– |
Ubuntu Pro 24.04 LTSflatpakpkg:deb/ubuntu/flatpak?arch=source&distro=esm-apps/nobleOther threats | Affected
| Fixed in– |
Ubuntu Pro 22.04 LTSflatpakpkg:deb/ubuntu/flatpak?arch=source&distro=esm-apps/jammyOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
Until a fix is available, avoid installing or updating Flatpak packages from untrusted OCI registries, especially on 32-bit systems.
Description
A heap buffer overflow vulnerability exists in Flatpak's OCI delta stream parser on 32-bit systems. The parser reads sizes as 64-bit values but passes them to GLib functions expecting 32-bit sizes, causing undersized allocations followed by overflows. An attacker controlling an OCI registry can exploit this during flatpak install or update to potentially achieve code execution.