CVE-2026-42420
OpenClaw < 2026.4.8 - Improper Base64 Decoding Size Validation
OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
What an attacker can affect
- Confidentiality
- None
- Integrity
- None
- Availability
- Low
Exploit likelihood
What each source reports
CVE List Score used
OpenClaw < 2026.4.8 - Improper Base64 Decoding Size Validation
OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input.
- Record
CVE-2026-42420- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-770
- Updated
- 2026-11-02
EUVDEUVD-2026-26123
OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input.
- Record
EUVD-2026-26123- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Updated
- 2026-11-02
GitHub AdvisoriesGHSA-ccx3-fw7q-rr2r
OpenClaw: Multiple Code Paths Missing Base64 Pre-Allocation Size Checks
Impact
Multiple Code Paths Missing Base64 Pre-Allocation Size Checks.
Several base64 decode paths could allocate before enforcing decoded-size limits.
OpenClaw is a user-controlled local assistant. This advisory is scoped to the OpenClaw trust model and does not assume a multi-tenant service boundary.
Affected Packages / Versions
- Package:
openclaw(npm) - Affected versions:
<=v2026.4.2 - Patched versions:
2026.4.8
Fix
The issue was fixed on main and is available in the patched npm version listed above. The verified fixed tree is commit d7c3210cd6f5fdfdc1beff4c9541673e814354d5.
Verification
The fix was re-checked against main before publication, including targeted regression tests for the affected security boundary.
Credits
Thanks @zsxsoft and @KeenSecurityLab for reporting.
- Record
GHSA-ccx3-fw7q-rr2r- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-770
- Updated
- 2026-11-02
NVD
OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input.
- Record
CVE-2026-42420- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/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 - CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - CVSS 3.1
- 6.5 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H - Weakness
- CWE-770
- Updated
- 2026-11-02
OSV
OpenClaw < 2026.4.8 - Improper Base64 Decoding Size Validation
OpenClaw before 2026.4.8 contains improper input validation in base64 decode paths that allocate memory before enforcing decoded-size limits. Attackers can exploit multiple code paths to cause memory exhaustion or denial of service through crafted base64-encoded input.
- Record
CVE-2026-42420- CVSS 4.0
- 5.3 Medium
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - Weakness
- CWE-770
- Updated
- 2026-11-02
OSVGHSA-ccx3-fw7q-rr2r
OpenClaw: Multiple Code Paths Missing Base64 Pre-Allocation Size Checks
Impact
Multiple Code Paths Missing Base64 Pre-Allocation Size Checks.
Several base64 decode paths could allocate before enforcing decoded-size limits.
OpenClaw is a user-controlled local assistant. This advisory is scoped to the OpenClaw trust model and does not assume a multi-tenant service boundary.
Affected Packages / Versions
- Package:
openclaw(npm) - Affected versions:
<=v2026.4.2 - Patched versions:
2026.4.8
Fix
The issue was fixed on main and is available in the patched npm version listed above. The verified fixed tree is commit d7c3210cd6f5fdfdc1beff4c9541673e814354d5.
Verification
The fix was re-checked against main before publication, including targeted regression tests for the affected security boundary.
Credits
Thanks @zsxsoft and @KeenSecurityLab for reporting.
- Record
GHSA-ccx3-fw7q-rr2r- CVSS 4.0
- 5.1 Medium
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N - CVSS 3.1
- 4.3 Medium
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L - Weakness
- CWE-770
- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
openclawnpm |
before 2026.4.8 | 2026.4.8 |
History
| Recorded | Changed | Sources |
|---|---|---|
| first indexed | CVE List, EUVD, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2026-42420 is a medium vulnerability (CVSS 5.3) in Openclaw, published April 9, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.30%, the 23rd percentile. Fixed in openclaw 2026.4.8.
References
github.com/openclaw/openclaw/security/advisories/GHSA-ccx3-fw7q-rr2r
vulncheck.com/advisories/openclaw-improper-base64-decoding-size-validation
nvd.nist.gov/vuln/detail/CVE-2026-42420