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01 Record

CVE-2026-6334

OAuth authorization code client binding not enforced during token redemption in Mattermost

LowPUBLISHEDCNA: Mattermost
CNA base score3.1 CVSS v3.xCVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N

02 Description

OAuth authorization code client binding not enforced during token redemption in Mattermost

03 Exploitation and scoring

Exploitation
Assessed, none found. CISA's assessment recorded neither public exploit code nor evidence of exploitation when it was made.
SSVC decision
  • ExploitationnoneCISA recorded no public exploit code and no evidence of exploitation.
  • AutomatablenoAt least one step from reconnaissance to exploitation cannot be reliably automated.
  • Technical ImpactpartialSuccessful exploitation gives limited control of the vulnerable component.
CISA publishes the decision points, not a final SSVC decision. The decision also depends on mission and well-being impact, which is a property of your deployment rather than of the vulnerability.
EPSS probability
0.11% probability of exploitation activity in the next 30 days.
EPSS percentile
Equal to or higher than the score of 1.5% of scored records. A rank, not a probability.
NVD base score
3.8 (CVSS v3.x), scored by the NVD independently of the CNA.
NVD CVSS vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:L/I:L/A:N
NVD analysis status
Analyzed. NVD last modified this record on 2026-10-14.
Red Hat severity
No Red Hat rating. Red Hat rates the CVEs that affect its products.

Exploit-prediction scores from FIRST. Independent scoring and analysis status from the NVD. Vendor severity from Red Hat. Exploitation assessment and catalog membership from CISA.

04 Metadata

Published
2026-05-18 06:33Z5 MO AGO
Last updated
2026-05-18 14:36Z5 MO AGO
Reserved
2026-04-15
Assigning CNA
Mattermost
Record state
PUBLISHED
Severity
Low (CVSS 3.1)
CNA CVSS vector
CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:L/I:L/A:N
Weaknesses
  • CWE-305Authentication Bypass by Primary WeaknessBase
Data version
5.2
Document digest
ab89568cba7adb2dcada559ec71c3598f1dde13b0ff522c5e9560fff3c645e80

05 Affected products

VendorProductVersionsPlatforms
MattermostMattermost11.5.0 to 11.5.1, 10.11.0 to 10.11.13—

06 References

07 Remediation

Update Mattermost to versions 11.6.0, 11.5.2, 10.11.14 or higher.