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TI-2026-82635 Aliases CVE-2026-118673

Out-of-bounds write in KeePassXC browser integration encryption

Priority MEDIUM 52CWE-787Published · Updated

Key facts

Attack vector
Local
Privileges required
Low
User interaction
Passive
Attack complexity
High
Attack requirements
Present
Impact type
Denial of service
Confidentiality · integrity · availability
None · None · High
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA. Impact type from CWE-787 and the CVSS impact.

Summary

KeePassXC from 2.3.0 before 2.8.0 is affected. The browser integration encrypts authorized responses into a fixed 1 MiB buffer, so large responses make encryption write past its end (CWE-787). A browser-protocol client with access to the per-user IPC endpoint and a valid database association can trigger this when an unlocked database generates a sufficiently large response.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

Description from the CNA

KeePassXC is a cross-platform community-driven port of the Windows application KeePass Password Safe. From 2.3.0 until 2.8.0, KeePassXC browser integration encrypts authorized responses in src/browser/BrowserMessageBuilder.cpp using a fixed 1 MiB output vector even though Botan::Sodium::crypto_box_easy() writes the plaintext length plus crypto_box_MACBYTES. A browser-protocol client that can access the per-user IPC endpoint, has a valid database association, and causes an unlocked database to generate and encrypt a sufficiently large authorized response can trigger a sequential out-of-bounds write before any response is delivered. This issue is fixed in version 2.8.0.

Why it matters now

Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00115 1st percentileScored 2026-11-07
Fix Fixed keepassxc (keepassxreboot): 2.8.0

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Poc
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
keepassxrebootkeepassxc2.3.0 to before 2.8.02.8.0Patch availableCNA
  • keepassxc Vendorkeepassxreboot Affected 2.3.0 to before 2.8.0 Fixed in 2.8.0 Patch available CNA

Remediation

Upgrade KeePassXC to version 2.8.0 or later.

Written with Claude Haiku 5.5 from the sources below · 2026-11-03

  • Fix · CNA keepassxc (keepassxreboot) Fixed in 2.8.0

Vendor assessments

Red Hat

Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat

Timeline

  1. 2026-10-29 Threatist record created from CVE-2026-118673
  2. 2026-10-30 Affected versions changed · Red Hat
  3. 2026-10-30 CVSS score added · Red Hat
  4. 2026-11-03 CISA SSVC decision points changed
  5. 2026-11-03 Priority changed: LOW → MEDIUM

References

Other 4

  • TI-2026-71790 Heap use-after-free in KeePassXC KDB importer CVSS 4.0MEDIUM 4.3

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences