How severe is GHSA-j944-w549-3453?

No CVSS score has been assigned to GHSA-j944-w549-3453 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-j944-w549-3453?

GHSA-j944-w549-3453 affects the following packages: cinny (npm). Ecosystems affected: npm.

How do I fix GHSA-j944-w549-3453?

Update cinny to 4.10.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j944-w549-3453 is resolved across your whole dependency graph.

How do I detect GHSA-j944-w549-3453 in my npm dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cinny. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-j944-w549-3453 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-j944-w549-3453?

O3 pinpoints whether GHSA-j944-w549-3453 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-j944-w549-3453 actively exploited in the wild?

No public exploit code has been indexed for GHSA-j944-w549-3453 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

When was GHSA-j944-w549-3453 published, and has it been updated?

GHSA-j944-w549-3453 was published on May 7, 2026 and was last updated on June 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

📦 npm

GHSA-j944-w549-3453

GHSA-j944-w549-3453 is a security vulnerability in cinny. O3 Security confirms whether GHSA-j944-w549-3453 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Cinny vulnerable to access token disclosure via invalidated emoji pack avatar URL in service worker

Also known asCVE-2026-42553

Published

May 7, 2026

Updated

Jun 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.

cinnynpm

3downloads / week

Description

Impact

A remote authenticated attacker who shares a room with a victim and has permissions to create room emotes (for example in a DM) can cause the victim's client to send their Matrix access token to an attacker-controlled server. This occurs when the victim opens the emoji or sticker picker for the room containing a malicious emote pack.

The root causes are:

(1) an incorrect fallback in EmojiBoard that uses untrusted pack.meta.avatar (user-controlled) without converting/validating it as an MXC URL, allowing arbitrary HTTP(S) URLs to be used; and

(2) the service worker attaching the user's Authorization bearer token to all outbound GET requests whose URL contains /_matrix/client/v1/media/download or /_matrix/client/v1/media/thumbnail without verifying the request host matches the configured homeserver origin. An attacker-controlled URL containing those path fragments and permissive CORS will receive the victim's Authorization header (access token).

Impacted users: anybody using affected Cinny web app versions who opens the emoji/sticker picker in a room containing a malicious emote pack and who is logged in (authenticated).

Patches

Version with fixes: https://github.com/cinnyapp/cinny/releases/tag/v4.10.3

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
📦npm	`cinny`	all versions	4.10.3

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for cinny. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update cinny to 4.10.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-j944-w549-3453 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-j944-w549-3453 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-j944-w549-3453. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Impact A remote authenticated attacker who shares a room with a victim and has permissions to create room emotes (for example in a DM) can cause the victim's client to send their Matrix access token to an attacker-controlled server. This occurs when the victim opens the emoji or sticker picker for the room containing a malicious emote pack. The root causes are: (1) an incorrect fallback in EmojiBoard that uses untrusted `pack.meta.avatar` (user-controlled) without converting/validating it as an MXC URL, allowing arbitrary HTTP(S) URLs to be used; and (2) the service worker attaching

O3 Security · Impact-Aware SCA

Is GHSA-j944-w549-3453 in your dependencies?

O3 detects GHSA-j944-w549-3453 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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