CVE-2026-28474: Nextcloud Talk allowlist bypass via actor.name display name spoofing

Should you act?

Critical and remotely reachable

No known exploitation yet, but it is network-reachable without credentials. This signal is computed from CISA KEV, EPSS and CVSS data; it is not an editorial verdict.

• No confirmed exploitation. It is not in CISA’s KEV catalog and CISA’s SSVC assessment records no known exploitation. That can change quickly after a public write-up; re-check if you are affected.
• EPSS 0.9%, percentile 59: FIRST’s model estimates a 0.9% chance of exploitation activity in the next 30 days, higher than 59% of all scored CVEs (moderate). EPSS is a probability, not a verdict.
• Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
• Only applies if your dependency tree includes @openclaw/nextcloud-talk (npm) <= 2026.2.2, fixed in 2026.2.6. Check your lockfile, including transitive dependencies.

What it is

OpenClaw's Nextcloud Talk plugin versions prior to 2026.2.6 accept equality matching on the mutable actor.name display name field for allowlist validation, allowing attackers to bypass DM and room allowlists. An attacker can change their Nextcloud display name to match an allowlisted user ID and gain unauthorized access to restricted conversations.

From the GitHub advisory

Summary

In affected versions of the optional Nextcloud Talk plugin (installed separately; not bundled with the core OpenClaw install), an untrusted webhook field (actor.name, display name) could be treated as an allowlist identifier. An attacker could change their Nextcloud display name to match an allowlisted user ID and bypass DM or room allowlists.

Details

Nextcloud Talk webhook payloads provide a stable sender identifier (actor.id) and a mutable display name (actor.name). In affected versions, the plugin’s allowlist matching accepted equality on the display name, which is attacker-controlled.

Affected Packages / Versions

Weakness type: CWE-863, CWE-290.

Product: @openclaw/nextcloud-talk (npm) · Assigned by: VulnCheck · Published: 2026-03-05

Affected and fixed versions

Severity scores

• Attack vector: network (remotely reachable)
• Attack complexity: low
• Attack requirements: none
• Privileges required: none (no login)
• User interaction: none

CVSS measures how bad a flaw is if exploited, not how likely exploitation is. Read it next to the exploitation data below.

Exploitation and urgency

• CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
• CISA SSVC assessment: exploitation none, automatable yes, technical impact total.
• FIRST EPSS (model of 2026-10-21): 0.88% probability of exploitation activity in the next 30 days; percentile 59.

Timeline

• 2026-02-17 — GitHub-reviewed advisory GHSA-r5h9-vjqc-hq3r published (critical)
• 2026-03-05 — CVE record published by VulnCheck
• 2026-09-17 — CVE record last updated

Sources and references

Original sources first. Version and fix details should always be confirmed against the vendor or project advisory.

Vendor and project advisories, patches

1. GitHub Security Advisory (GHSA-r5h9-vjqc-hq3r) github.com
2. Patch Commit #1 github.com

Vulnerability records

1. GitHub Advisory GHSA-r5h9-vjqc-hq3r github.com
2. CVE.org record CVE-2026-28474 cve.org
3. NVD entry CVE-2026-28474 nvd.nist.gov

Other references from the CVE record and advisory

1. VulnCheck Advisory: OpenClaw Nextcloud Talk < 2026.2.6 - Allowlist Bypass via actor.name Display Name Spoofing vulncheck.com
2. github.com github.com
3. github.com github.com

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