# CVE-2026-77353: Wallos: iCalendar Injection via CRLF in Subscription Name/Notes Export

> Authenticated users can inject malicious iCalendar events via CRLF in subscription names, affecting all subscribers to the feed.

- **Severity:** Medium 4.6 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:L/I:L/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 31 Aug 2026
- **Updated:** 3 Sep 2026
- **Also known as:** GHSA-q2r8-m9wm-5547

## What is CVE-2026-77353?

CVE-2026-77353 is a medium-severity vulnerability in ellite Wallos, published on 31 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

Wallos is an open-source, self-hostable personal subscription tracker. Prior to version 5.0.0, Wallos allows authenticated users to inject arbitrary iCalendar properties and events into their exported .ics feed by embedding raw CRLF sequences in subscription names or notes. Because the input validation layer only encodes HTML metacharacters but never strips newlines, and the export layer decodes those entities back before writing iCal output, an attacker with any valid account can craft a subscription whose name breaks out of the current VEVENT block and inserts fully attacker-controlled calendar events — including spoofed organizers, arbitrary email addresses in ATTENDEE properties, and misleading event content — into any calendar application subscribed to that feed. This issue has been patched in version 5.0.0.

Weakness: CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component), CWE-116 (Improper Encoding or Escaping of Output)

## Which versions are affected by CVE-2026-77353?


## How do I fix CVE-2026-77353?

No fix has been published for CVE-2026-77353 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-77353 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77353 exists.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-77353 and fix it if it is affected.

What it is: CVE-2026-77353 is a medium-severity vulnerability in ellite Wallos, published on 31 Aug 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-77353 exists.

Affected product: ellite Wallos. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-77353/ (Markdown: https://insights.sbomify.com/CVE-2026-77353/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-77353
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-77353
- OSV: https://osv.dev/vulnerability/CVE-2026-77353

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-77353/
Summaries are generated and may contain mistakes; the official description above is the record.