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CVE-2026-35646

OpenClaw < 2026.3.25 - Pre-Authentication Rate-Limit Bypass in Webhook Token Validation

6.3 MediumFix available

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Attack profile

How easy it is to exploit

Attack vector
Network
Complexity
High
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
Low
Integrity
Low
Availability
None

Exploit likelihood

0.25%Up 0.2 points since Apr 10, 2026
90%50%10%1%

What each source reports

CVE List Score used 6.3

OpenClaw < 2026.3.25 - Pre-Authentication Rate-Limit Bypass in Webhook Token Validation

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
CVE-2026-35646
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
CVSS 3.1
4.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-307
Updated
2026-11-02
EUVDEUVD-2026-21144 6.3

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
EUVD-2026-21144
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Updated
2026-11-02
GitHub AdvisoriesGHSA-59xc-5v89-r7pr 6.3

Duplicate Advisory: OpenClaw: Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Webhook Token

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-mf5g-6r6f-ghhm. This link is maintained to preserve external references.

Original Description

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
GHSA-59xc-5v89-r7pr
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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
4.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-307
Updated
2026-11-02
GitHub AdvisoriesGHSA-mf5g-6r6f-ghhm 6.3

OpenClaw: Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Webhook Token

Summary

Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Weak Webhook Token

Affected Packages / Versions

  • Package: openclaw
  • Affected versions: <= 2026.3.24
  • First patched version: 2026.3.25
  • Latest published npm version at verification time: 2026.3.24

Details

Synology Chat webhook auth previously rejected invalid tokens without throttling repeated guesses, allowing brute-force attempts against weak webhook secrets. Commit 0b4d07337467f4d40a0cc1ced83d45ceaec0863c adds repeated-guess throttling before auth failure responses.

Verified vulnerable on tag v2026.3.24 and fixed on main by commit 0b4d07337467f4d40a0cc1ced83d45ceaec0863c.

Fix Commit(s)

  • 0b4d07337467f4d40a0cc1ced83d45ceaec0863c
Record
GHSA-mf5g-6r6f-ghhm
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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-307, CWE-521
Updated
2026-11-02
NVD 6.3

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
CVE-2026-35646
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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
4.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
CVSS 3.1
6.5 MediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-307
Updated
2026-11-02
OSV 6.3

OpenClaw < 2026.3.25 - Pre-Authentication Rate-Limit Bypass in Webhook Token Validation

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
CVE-2026-35646
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N
Weakness
CWE-307
Updated
2026-11-02
OSVGHSA-59xc-5v89-r7pr 6.3

Duplicate Advisory: OpenClaw: Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Webhook Token

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-mf5g-6r6f-ghhm. This link is maintained to preserve external references.

Original Description

OpenClaw before 2026.3.25 contains a pre-authentication rate-limit bypass vulnerability in webhook token validation that allows attackers to brute-force weak webhook secrets. The vulnerability exists because invalid webhook tokens are rejected without throttling repeated authentication attempts, enabling attackers to guess weak tokens through rapid successive requests.

Record
GHSA-59xc-5v89-r7pr
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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
4.8 MediumCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:N
Weakness
CWE-307
Updated
2026-11-02
OSVGHSA-mf5g-6r6f-ghhm 6.3

OpenClaw: Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Webhook Token

Summary

Synology Chat Webhook Pre-Auth Rate-Limit Bypass Enables Brute-Force Guessing of Weak Webhook Token

Affected Packages / Versions

  • Package: openclaw
  • Affected versions: <= 2026.3.24
  • First patched version: 2026.3.25
  • Latest published npm version at verification time: 2026.3.24

Details

Synology Chat webhook auth previously rejected invalid tokens without throttling repeated guesses, allowing brute-force attempts against weak webhook secrets. Commit 0b4d07337467f4d40a0cc1ced83d45ceaec0863c adds repeated-guess throttling before auth failure responses.

Verified vulnerable on tag v2026.3.24 and fixed on main by commit 0b4d07337467f4d40a0cc1ced83d45ceaec0863c.

Fix Commit(s)

  • 0b4d07337467f4d40a0cc1ced83d45ceaec0863c
Record
GHSA-mf5g-6r6f-ghhm
CVSS 4.0
6.3 MediumCVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:L/VI:L/VA:N/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-307, CWE-521
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
openclaw
npm
 before 2026.3.28
2026.3.28

History

History
RecordedChangedSources
affected
first indexedCVE List, EUVD, GitHub Advisories, NVD, OSV

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

In short

CVE-2026-35646 is a medium vulnerability (CVSS 6.3) in Openclaw, published March 29, 2026. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.25%, the 16th percentile. Fixed in openclaw 2026.3.28.

References

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