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CVE-2026-118673

KeePassXC: Out-of-bounds write in browser integration response encryption with oversized database responses

4.1 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Local
Complexity
High
Privileges needed
Low
User interaction
Passive

What an attacker can affect

Confidentiality
None
Integrity
None
Availability
High

Exploit likelihood

0.11%Unchanged since Oct 30, 2026
90%50%10%1%

What each source reports

CVE List Score used 4.1

KeePassXC: Out-of-bounds write in browser integration response encryption with oversized database responses

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.

Record
CVE-2026-118673
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-787
Updated
2026-11-03
EUVDEUVD-2026-113213 4.1

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.

Record
EUVD-2026-113213
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-03
NVD 4.1

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.

Record
CVE-2026-118673
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Weakness
CWE-787
Updated
2026-11-03
OSV 4.1

KeePassXC: Out-of-bounds write in browser integration response encryption with oversized database responses

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.

Record
CVE-2026-118673
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Weakness
CWE-787
Updated
2026-11-04
OSVDEBIAN-CVE-2026-118673 4.1

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.

Record
DEBIAN-CVE-2026-118673
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Updated
2026-11-04
OSVUBUNTU-CVE-2026-118673 4.1

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.

Record
UBUNTU-CVE-2026-118673
CVSS 4.0
4.1 MediumCVSS:4.0/AV:L/AC:H/AT:P/PR:L/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
keepassxc
Debian:12
All versions, plus listed versions
2.7.10+dfsg1-12.7.10+dfsg1-22.7.10+dfsg1-2.12.7.4+dfsg.1-22.7.6+dfsg.1-1
Show 7 moreShow less
2.7.7+dfsg.1-12.7.7+dfsg.1-1+exp12.7.7+dfsg.1-22.7.7+dfsg.1-32.7.7+dfsg.1-3~exp12.7.9+dfsg1-12.8.0+dfsg1-1
None known
keepassxc
Debian:13
All versions, plus listed versions
2.7.10+dfsg1-12.7.10+dfsg1-22.7.10+dfsg1-2.12.8.0+dfsg1-1
None known
keepassxc
Debian:14
before 2.8.0+dfsg1-1, plus listed versions
2.7.10+dfsg1-12.7.10+dfsg1-22.7.10+dfsg1-2.1
2.8.0+dfsg1-1
keepassxc
Ubuntu:18.04:LTS
All versions, plus listed versions
2.2.2-12.2.3+dfsg.1-12.2.4+dfsg.1-12.3.0+dfsg.1-0ubuntu22.3.1+dfsg.1-1
None known
keepassxc
Ubuntu:20.04:LTS
All versions, plus listed versions
2.4.3+dfsg.1-12.4.3+dfsg.1-1build1
None known
keepassxc
Ubuntu:22.04:LTS
All versions, plus listed versions
2.6.6+dfsg.1-1~exp12.6.6+dfsg.1-1
None known
keepassxc
Ubuntu:24.04:LTS
All versions, plus listed versions
2.7.4+dfsg.1-22.7.6+dfsg.1-12.7.6+dfsg.1-1build22.7.6+dfsg.1-1build3
None known
keepassxc
Ubuntu:26.10
All versions, plus listed versions
2.7.10+dfsg1-2ubuntu12.7.10+dfsg1-2.12.7.10+dfsg1-2.1build1
None known
keepassxc
Ubuntu:26.04:LTS
All versions, plus listed versions
2.7.10+dfsg1-12.7.10+dfsg1-22.7.10+dfsg1-2ubuntu1
None known

History

History
RecordedChangedSources
affected, factsEUVD, NVD, OSV
facts, referencesCVE List
first indexedCVE List, EUVD, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2026-118673 is a medium vulnerability (CVSS 4.1) in Keepassxc, published October 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.11%, the 1st percentile. Fixed in keepassxc 2.8.0+dfsg1-1.

References

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